Smog Check OBD II (OBD 2) : What are Readiness Monitors ?

check engine lightOBD II, “CHECK-ENGINE” LIGHTS,  and READINESS MONITORS..WHAT ARE THEY?

OBD II is a system that has been installed in most 1996 and later cars and light trucks, intended to inform the driver of problems in the components that control the engine and transmission. The primary reason OBD II was invented is to reduce smog emissions caused by malfunctions, but it is also valuable as an alert to the driver that something is wrong…something that can affect gas mileage and drivability, or actually cause further damage to the vehicle.

While you are driving your vehicle, its computer is constantly monitoring and running tests on the various sensors, actuators and electrical parts that make the car run properly. If a problem is detected, a Diagnostic Trouble Code (DTC) is set, and the computer turns on the “Check Engine” light. (The light may say “CHECK ENGINE”, “SERVICE ENGINE SOON” or merely be an icon that looks like an engine.)

What are “Monitors”?

Even if there are no problems with your car, the results of tests that have been run are stored in the computer as having been completed. The status of these tests (complete or incomplete) is referred as the “readiness monitors”.  When your car gets a smog test, one portion of the test involves connecting the smog test machine to the car’s computer and checking if there are any DTC’s, and also checking to see if the monitors are ready. If they are not, the vehicle fails the test, because there may be problems in the system that can’t be reported by the computer.

There are several reasons why the monitors may be incomplete. If your car has recently been repaired for a problem that set a DTC (check engine on) and the technician cleared the DTC, he also erased the monitors. Also, if battery has been disconnected, replaced or needed a jump-start, the monitors may be erased.

In earlier systems (OBD I) there was no long-term record stored of the state of the car’s systems. If a problem turned on the check-engine light, a simple battery-disconnect could turn it off long enough to pass a smog test, even though the problem was still there.  OBD II helps ensure that the vehicle is in proper condition to run clean.

My car passed the emissions test…who cares if the monitors are incomplete?

The overall smog inspection consists of three parts…the emissions test,  which measures the smog coming out of the tailpipe; the visual inspection, to look for broken or modified parts; and the functional tests, where other systems are checked to see if they are working properly. The OBD II test is a functional test.

As sophisticated as the emissions test has become, it still only tests your car under very limited conditions… accelerating at 15mph and cruising at 25mph, with the engine warm. It does not test what is going on when the engine is cold, idling, decelerating, etc. Also, not all the smog a car makes comes out the tailpipe. Gasoline fumes that evaporate from your fuel tank, and crankcase fumes that collect in the lower part of the engine can escape into the air and create smog. The systems that control these are not tested during the emissions test, so the visual inspection and OBD II test are needed to check them.

OK, my monitors are incomplete…how do I complete them?

Basically, drive the car. There are specific driving conditions that must be met in order to run various tests, but most of them can be met in normal driving. One thing that helps is to cruise at a steady speed for several minutes, so a ten-mile freeway drive in light traffic is a good bet. Keep a steady foot on the gas rather than speeding up and slowing unneccesarily.

Note that a car can pass with some incomplete monitors…a maximum of one on 1999 and earlier cars, and only one (The Evaporative System monitor) on model year 2000 and later gasoline powered automobiles.

All monitors must be complete on 1998-2006 diesel powered vehicles.  Any two (2) monitors may be incomplete on 2007 and newer diesels.

Some tests only run when the car sits overnight, or is allowed to cool down for several hours. Most cars will complete the monitors easily with the above methods, but rarely it will take up to several weeks before they are complete. Some auto repair shops will run drive cycles, a specific driving routine, to complete monitors more quickly.

My mechanic told me my check engine light is on because of a short circuit in the light, and there is nothing wrong with the emission system.

Though this may be true (rarely), the check engine light is part of the emission system and needs to be working properly for the car to pass. If it has a short, the short must be fixed.

OBD Testability Issues

Some vehicle models are known to have issues that interfere with the successful completion of OBD readiness monitors.  The State of California Bureau of automotive repair maintains a list of these vehicles and specific remedies, if known, that can assist a motorist in completing monitors.  In some cases repairs may be required, and in others test equipment is programmed to ignore some or all readiness monitors on affected vehicles.

To learn more about OBD readiness monitors and testability issues, please download the Smog Check OBD Reference from the Bureau of Automotive Repair website.

66 thoughts on “Smog Check OBD II (OBD 2) : What are Readiness Monitors ?”

    1. It depends on what you mean by “fails monitor test”. If you mean that your 1997 Sonoma is not completing the EVAP monitor (Not ready, incomplete, etc), that is the only incomplete monitor, and nothing else is wrong with your vehicle, then yes, it can pass the smog inspection. If you mean that the monitor runs, and sets a DTC (Check engine light comes on), then no, it will not pass until it is repaired.

  1. My 2001 Chevy van has less than 3000 miles on it and the battery needed replacement, so I have been trying to put some miles on the odometer; however, driving on the freeways is a “joke” as to steady speed data storage.

    If my truck has always been able to pass prior year’s tests, why is a “STAR” certification required this time?

    Resp,
    Jack

    [Editors Note: Original comment was retyped, but not changed, to improve readability.]

    1. The Bureau of Automotive Repair directs a portion of vehicles requiring a smog inspection to STAR certified stations. (Both licensed
      Test Only stations and licensed Test and Repair stations may qualify for STAR certification).
      Currently, these directed vehicles fall under two categories:

        High Emitter Profile – The High Emitter Profile (HEP) is a statistical model used to identify vehicles more likely than others to fail a Smog Check inspection. Vehicles identified by the HEP must receive certification at a STAR certified Test Only station or STAR certified Test and Repair station.

        A vehicle that “has always been able to pass” may still be included in the “High Emitter Profile” group. That’s because High
        Emitter refers to the year, make and model instead of a specific vehicle’s performance.

        2% Random Sample – For program evaluation purposes, 2% of the vehicles in Enhanced Areas are randomly selected for certification at a STAR Test Only station or STAR Test and Repair station. Directed vehicles can only receive Smog Check certification from STAR Test Only or STAR Test and Repair stations.

      Either way, the important thing to remember is that there should be absolutely no difference between a smog inspection/test performed at a STAR Station and an inspection/test performed at a “regular” shop. The only difference is that in order to inspect and certify directed vehicles, a STAR station is required to meet stricter performance thresholds than “regular” smog shops.

  2. Thank you for explaining the smog check process in simple terms….I’ve gone nuts trying to understand why the tailpipe emissions are not enough,never really understood “Functional” testing.

  3. i went to get my truck smogged and everything passed but the OBD system checks fails, so the smogg guy told me to go and drive it around, so i did. i did well over 40 miles, drove it all weekend to different cities and i took it in monday morning, and its still not working. my check enegin light has not came on, and he asked if i had needed a jump or unplugged the battery, i said i have not, and he stated that my computer in the truck keeps reseting itself. its a 98 ford ranger, and im kinda stuck from here on what to do.
    is it fuse oe sencer that needs to be replaced or what.?
    hope yoou can help

    1. Hi Samantha, I’m sorry that your truck is having difficulty completing OBD II readiness monitors. I understand how frustrating that can be.

      While most vehicles complete monitor readiness in a short amount of time during normal driving, other vehicles can present more of a challenge.

      In some cases its a matter of driving habits. Most monitors run during steady driving conditions while others (The catalytic converter monitor on some many vehicles) require stop and go traffic.

      You could try looking on line for OBD drive cycles specific to your year make and model vehicle.

      Also, some vehicles are known to have OBD testability issues. The State of California Bureau of Automotive repairs maintains a list of these vehicles in a PDF document located at http://www.bar.ca.gov/pdf/Smog_Check_OBD_Reference_Guide.pdf.

      It’s also possible that a defective component in your vehicle may be preventing your vehicle from completing readiness monitors. Your best bet is to take your vehicle to a qualified smog “test and repair” shop where they can diagnose the cause of the problem and repair your vehicle. You can find a list of repair shops at http://www.smogcheck.ca.gov/pubwebquery/station/stationlist.aspx.

  4. I have a 2004,the codes and monitors were cleared by the smog tech by accident,I hear there’s o button on OBD that will do that, I have tryed 3 different drive cycles I found from smog techs, online and GM dealer, I’ve also been driving it daily and logged up 2500 miles over the last 2 months, what the heck am I suppose to do

    1. While the BAR OIS does not have a button “that will do that”, it’s possible that he was using a handheld scanner that would.

      In addition to following the specific drive cycle recommended by the manufacturer for your year, make, and model vehicle, you also want to ensure that there’s not another issue with your vehicle that is preventing the monitors from running to completion.

      After 2,500 miles without success, I’d suggest taking your vehicle to a qualified emissions repair technician who may be able to diagnose your vehicle’s problem.

  5. i just got catalyst system maintained and cleared but my light popped back on with the same code my mech said that it might be on due to the fact that its still clearing from the old leaks and should go off and my car keeps rejecting the emission test what should I do .
    ?

    1. Meesha, based on the information that you provided, it’s not possible for me to provide answers specific to your situation, but generally speaking it is not likely that the “light popped back on… due to the fact that it’s still clearing from old leaks”. Unfortunately, it is also unlikely that the light will “go off” without further repairs.

      Most diagnostic trouble code setting faults are “two trip faults”. In the case of a two trip fault, the first instance of the fault does not turn on the check engine light. Instead the details of the fault are stored in memory pending a repeat of the same fault under similar conditions. The check engine light does not come on until the second time the fault is detected.

      Assuming that your mechanic cleared (turned off) the check engine light after repairing your vehicle, your vehicle’s on board diagnostic system would have no memory of “old leaks”. Even if old data remained, your vehicle’s computer would wait until it detected the same fault a second time before turning on the check engine light. To make a long story short, an old problem will not turn on your check engine light.

  6. I tryed to do a smog on my car n they say its good but when they try to finish up the test they saying its not finishing up an it stops at 91% n wont finish it up to print the smog paper why is it doing that?

  7. I just came back from the smog and the cat said its not ready. Everything else was. The mechanic said I need to drive more miles, but I have driven about 1.5k miles within a month. The mechanic said that’s the only way to pass the smog. However my car is from 2000 and I am trying to find how many monitors I am allowed to fail and if that would qualify…
    Thanks for your help!

    1. In order to pass the smog inspection, only the EVAP monitor can be incomplete on model year 2000, and newer, gasoline powered vehicles. The state does make allowances for certain vehicles that are known to have testability issues that prevent monitors from running to completion (Read more about OBD II Monitors and Testability Issues here). However, in most cases, after 1,500 miles of driving, I’d suspect that a defective component is preventing the catalyst monitor from running to completion.

  8. Hey..I just bought a 2001 Mitsubishi Eclipse GT but the guy said it won’t pass smog and it needs to be driven longer…I drove it about 60 miles back home(plus whatever he did) and when I got home I swapped the battery…I was told that me doing that reset the drive cycle and it still won’t pass so what do I need to do to find out what the [actual] problem with my car is??? Please and thank you

    1. Unfortunately, completing OBD II readiness monitors on 2001 Mitsubishi Eclipse model vehicles can be extremely difficult. Mitsubishi has issued a technical service bulletin (TSB) detailing this problem and drive cycle suggestions for running the monitors to completion (Available here).

      It is important to remember that disconnecting the battery, clearing the computer, resetting diagnostic trouble codes, or any other action that interferes with your car’s “computer memory” will result in your having to “start over”.

  9. My 2004 Toyota Highlander has a CAT sensor that has not reset after disconnecting the battery several months ago, and will hence not pass the smog. The model is listed in Table 3 of the OBD reference guide with the cause listed as “Monitors can be difficult to complete.” Since the model is listed in Table 3, does that mean I can get an exemption? If so, is this something that can be done at the original test station or do I need to take it somewhere else?

    1. Hi Andre, I took a look at the Smog Check OBD Reference, and while it does indicate that “Monitors can be difficult to complete”, the “Instruction to Inspector” column indicates “Follow drive cycles in Toyota service information. Test normally”. So, unfortunately, it does not appear that BAR would issue an “exemption” for your vehicle.

      CATALYST MONITOR DRIVE CYCLE INSTRUCTIONS

      1. The monitor will not run if active diagnostic codes are present
      2. Do not turn off the ignition switch during the test procedure.
      3. Allow the vehicle to run at idle until fully warmed up. I usually recommended letting it idle for ten to fifteen minutes after sitting overnight.
      4. After warming up the vehicle, drive at a steady speed between 40 & 70 miles per hour. Tip: try to stay around the middle of this range (55MPH). Also, in Southern California, it may only be possible to maintain these speeds early on a weekend morning.
      5. You may need to extend the drive cycle.
      6. In most cases, you should be able to complete the catalyst monitor after following the drive cycle a couple of times.

      If several reasonable attempts at running the drive cycle fail to complete the catalyst monitor, a problem may exist that is preventing your vehicle from running the monitor to completion. In that case, it may be time to have your vehicle properly diagnosed and repaired by a shop that has the training, equipment, and experience necessary to diagnose and repair OBD monitor issues.

  10. Hello,
    I have a Toyota Corolla 1998. My battery was stolen over a month ago. I put a battery 3 weeks ago. I been driving the car for 2 weeks already. They day I went to do the smog check my car didn’t want to turn on. I noticed that holder came off. I put it back and didn’t drive it for 3 hours. Then I went over to the smog check place which was across the street where I was. The car didn’t pass the OBD section. The guy told me to drive that car for 80 miles. I haven’t yet. Do I have to drive all 80 miles?

    1. The simple answer is maybe. Eighty miles is a good rule of thumb because most cars will complete OBD readiness monitors within eighty miles; however, many cars will complete them in less, while some can take a whole lot more. One solutions would be to purchase an inexpensive code reader and check monitors as you go.

    2. Yes, but also, some vehicles will reset/clear monitors when vehicle is turned off. Recommend on vehicles prior to 2001 to drive at least 50 miles and before turning off vehicle have shop scan OBII for proper monitor operation. If ok, shut off vehicle and recheck later to see if monitors have preformed it’s diagnostics and maintained memory. If not, dive 40-50 miles and recheck and smog. DO NOT TURN OFF VEHICLE. This should work. Later OBII systems retain prior drive cycles information and scans sensors and monitors faster due to processor. Understand that earlier EEC systems have to learn as you drive and monitors are operated in a series, until all emission, fuel and engine sensors are operating properly.

  11. I have a 2004 suburban, it failed the state inspection because the Catalyc and Evap sensors were not ready. I had not done any repairs or disconnect the battery, so I took it to the dealer where they did a drive cycle and on the paper work it said that the drive cycle was completed and both monitors were ready. I drove directly to get the inspection done and it failed again for the same symptom. I took it back to the dealer and they told me that somehow monitors were resetting, so they were going to do more tests. Now they said that the catalyst converter is defective and needs to be replaced. Will a defective Catalys convereter cause the ECM to reset the monitors? If the catalyst was defective I would think the service engine light would come on and stay on alerting of an issue with the catalys. Any thoughts?

    1. Frank, I’m inclined to agree with you. OBD II is designed to function exactly as you described at the end of your comment. I’d be more inclined to believe that something else is causing the monitors to reset (Low cranking voltage, or other factors that may interrupt power to the PCM), or that the dealer inadvertently failed to complete monitors the first time.

  12. Hello Julius,

    My 2000 Toyota Camry did not pass smog. I live at Concord, California. The technician asked me to do a full drive cycle which I did for 2 weeks. I almost drove 100 miles. I am using OBD 2, From the 2 Incomplete it went to down to one. My check engine light is off. The technician is saying that the next time he checks my car and with one incomplete, he told me to bring it to a mechanic.

    Please help. There is no error code on my the reading of my OBD 2. I am using Actron CP9125

    1. While 1999 and older model year vehicles can still pass the smog inspection with one incomplete readiness monitor, only the EVAP monitor can be incomplete on 2000 and newer model year vehicles.

      Allowing that you are meeting the requirements of the Toyota drive cycle, it sounds like the technician is giving you good advice. Start with the monitor that is not running to completion and look for issues that would affect that specific system.

  13. BUEN DIA SOY DE MEXICO Y ESTO DE LOS MONITORES ESTA LLEGANDO POR ESTE LADO ,,, MI PREGUNTA… HABRA UN SIMULADOR O ALGUN APARATO QUE EN LUGAR DE CONECTARSE AL OBD DEL VEHICULO ,, SE CONECTE AL SIMULADOR Y PASE LOS MONITORES LISTOS??…

  14. Hello,I have a 2005 Nissan Frontier SE and I added dual exhaust paid $700 and ever since check engine light comes on,I bought a $300 programmer so I can clear the light but wouldn’t pass inspection still and the light comes after 75 miles,my garage wants all most $3000 to fix it because they say it’s the catalyst converter and the sensors,the cleared it last year but it cost me $250 to get the sticker and they said they did a fuel injection flush but I believe they didn’t and light cam back on after 75 just like my programmer did.Any advise would be greatly appreciated,thank you Kenny

    1. Hi Kenneth, it sounds like you have enough going on with your vehicle that your question is beyond the scope of what we can address over the internet. Hopefully everything works out in the end.

  15. My 2003 Dodge Caravan was given an incomplete on all parts of the smog check in NV, I was told to drive the vehicle and come back. I drove 2600 miles and then went for a recheck a week later and it came back with an incomplete again. I was then told to drive it for about 60 miles and come back again. What could be causing an incomplete? I had recent repair done a week before the 1st smog check, could something have been disconnected to cause this?

    1. Hi Linda, sorry about the late reply.

      I’m assuming that the check engine light is not on, so it’s a safe bet that nothing was left disconnected.

      You want to make sure that you’re following the manufacturers suggested drive cycle for your vehicle, and that there are no active recalls or campaigns related to your vehicle. In many cases, especially with Chrysler vehicles, the manufacturer periodically issues firmware updates in order to address issues related to the car’s “computer”. Such issues can often prevent monitors from running to completion.

      Also, your mechanic may be able to diagnose a problem that is on the verge of turning on the check engine light, but isn’t quite there. A component that is close to failure can delay or prevent the completion of readiness monitors. Just mention mode six data to your mechanic. If he gives you a glazed look, consider having the problem diagnosed at another shop.

  16. Hi Julius,

    I have a 2000 Toyota Camry. I went to check it with my OBD11 and found the following:

    0 (zero) error code
    2 Incomplete
    6 ready

    Is my car going to pass smog this time?

    1. Assuming that you are in the State of California, the answer is no.

      The EVAP monitor is the only incomplete monitor allowed on 2000 and newer gasoline powered vehicles.

  17. I have a 1999 Chevy Prizm (Corolla) with CAT and EVA monitors both not ready after erasing codes. I got EVA ready easily last time I did this, but no luck this time. Someone mentioned gas tank level might be a factor, your thoughts?

    1. The EVAP monitor is often a difficult monitor to run to completion. For that reason, in the State of California, 1996 – 1999 model year gasoline powered vehicles can pass the OBD II functional portion of the smog inspection with any one incomplete monitor, while 2000 and newer can pass if EVAP is the only incomplete monitor.

      Factors that can affect the EVAP monitor can include ambient temperature and fuel level. In most cases the EVAP monitor will not run if fuel level is below a quarter tank, or above three quarters of a tank.

  18. Hello I have 2006 chrysler Sebring touring and my o2 sensor and Cadillac converter sensors aren’t reading ive replaced a battery and computer around 7 months ago I have driven everyday since then…was told recently to drive an extra 50 to 70…so I ended up driven close to 150 city and freeway but those sensors still arent ready…it was three but now its down to two…my registration is well over due so driving is high risk for pull over and possible tow..also I have no check engine on…can u give me some advice please

    1. Hi Michael;

      You and Linda have similar issues (The comment above yours).

      As I suggested to Linda, you want to make sure that you’re following the manufacturers suggested drive cycle for your vehicle, and that there are no active recalls or campaigns related to your vehicle. In many cases, especially with Chrysler vehicles, the manufacturer periodically issues firmware updates in order to address issues related to the car’s “computer”. Such issues can often prevent monitors from running to completion.

      Also, your mechanic may be able to diagnose a problem that is on the verge of turning on the check engine light, but isn’t quite there. A component that is close to failure can delay or prevent the completion of readiness monitors. Just mention mode six data to your mechanic. If he gives you a glazed look, consider having the problem diagnosed at another shop.

    1. Hi Andrea,

      Abbreviations will vary depending on the scanner or code reader that you are plugging into your vehicle’s diagnostic data connector; however, the important thing to remember is that in order for your 2001 Mercury (And most other 2000 and newer gasoline powered vehicles) to pass a smog inspection in the State of California, the EVAP (Sometimes abbreviated as EVA) monitor is the ONLY monitor that can be incomplete.

  19. have a 2004 dodge ram 1500 5.7 hemy replaced my egr valve yesterday and went to get smoged today didnt pass due to obd monitor not ready evaporative system what do i do next.

    1. Basically, drive the car. There are specific driving conditions that must be met in order to run various tests, but most of them can be met in normal driving. One thing that helps is to cruise at a steady speed for several minutes, so a ten-mile freeway drive in light traffic is a good bet. Keep a steady foot on the gas rather than speeding up and slowing unnecessarily.

      Note that a car can pass with some incomplete monitors…a maximum of any one on 1999 and earlier cars, and only one (The Evap System monitor) on model year 2000 and later gasoline powered automobiles.

  20. My 2000 Dodge Grand Caravan continues to fail the readiness part of the smog test. Can I retire the car via the cash for clunkers program?

    1. Yes, if you meet the program requirements, you could retire your vehicle on the Bureau of Automotive Repair’s (BAR) Consumer Assistance Vehicle Retirement Program. You can learn more about BAR’s Consumer Assistance Program here and here. here.

  21. 03 acura rsx type s. I have question, i bought the car to a friend of mine and the car hasn’t move or drove for a year. But he replace the battery already so i took the car to do smog and it fails. Everything else pass except OBD2 not ready. Smog guy told me to drive cycle so I drove the car and added only 15 miles to the car. idk if i should drive it more miles or what. Can you help me and explain it?

    1. We normally recommend that customers run through the drive cycle two to three times; however, on a late model Acura you should be able to check if your vehicle is ready to test by following these steps:

      • Turn the ignition to the ON (II) position without starting the engine
      • The MIL (Check Engine Light) will come on for 20 seconds
      • After 20 seconds, one of two things will happen. It will either go off, or it will blink five times.
      • If it goes off (Without blinking five times) your vehicle should be ready to test.
      • If the check engine light blinks five times before turning off, continue to run the drive cylce. Your vehicle is not ready to test
  22. Thanks! It blink five times and i guess it’s not ready for test. So How far or many miles am i supposed to do the drive cycle? And do i just keep driving even though it’s not 55mph? Can you tell me the step how to do drive cycle?

    1. Which monitors weren’t ready when you had the vehicle tested. The monitors that weren’t ready should be listed about two thirds of the way down on the inspection report.

  23. I drive a 2010 Toyota Corolla. Went to get a smog and it failed the emissions. Even though the smog failed at the test only station, can I go to another no test station to get the smog again? Or does the information go to DMV already as he’s doing the test?

    1. Hi Stephanie,

      A common misconception among people whose vehicles fail a smog inspection is that they have to go back “and finish” the test. The truth is that the failed test is finished. The car failed. In other words, he is no longer “doing the test”, so you can take your car to any smog test station you would like; however, if you were directed to take your car to a “STAR Station” (SMOG Certification Required at a STAR station, or in some cases some DMV paperwork still says “test only”), then you need to make sure to go to a STAR station.

      No matter where you take it (Even if you return to the original station), a new inspection will be performed from start to finish.

  24. Hello, I just took my car to get smogged today I got my oil changed first then took it to get smogged, I drove my normal route to work which is approximately 15-20 min from home and then to get my oil changed another 15-20 min then to get it smogged 5 min away. They said I didn’t pass smog because my it wasn’t ready yet stating it couldn’t read it yet. I don’t have any check engine light on or any lights that could cause it to fail. After they told me to drive it and bring it back I drove it for about 10-30 min and brought it back and it still wasn’t able to pass still saying it wasn’t ready? May anybody here know why?

    1. We have a several good articles here at the Just Smogs® blog that explain readiness monitor failures (Smog Check OBD II (OBD 2): What are Readiness Monitors? and OBD II Monitor Drive Cycle Service are great examples).

      The quick answer is that if the computer in your car loses power for any reason, or if diagnostic trouble codes are cleared following repairs, you typically will have to drive your car between fifty to one-hundred miles (not minutes) before it will be ready to pass a smog inspection. It can take more or less miles than that, but fifty to one-hundred miles is the general rule of thumb.

  25. I am required to get a smog check on my 2007 VW Rabbit. The engine light was on so I took it to an Aamco Transmission before I get it smog checked. Aamco was able to detect two codes. I was told that I needed the gas cap replaced so I did. They reset the computer to clear the engine light on the dashboard. I went to a smog check station, and I was told to drive it for another 20 miles because they are getting, “OBD Not Ready/Incomplete”. So I drove another 30 miles, and ended up taking it to another smog check station where I was, and they also got the same error code of “OBD Not Ready or Incomplete”. I was told by that smog check station to take my car to a mechanic. I took my car to a mechanic, and they told me that I did not pass or fail the smog check, the print out only tells me that my car is not ready for the smog check, so they suggested for me to drive another 80 miles, and have it re-checked. How many miles do you have to drive your car in order for the smog test machines able to read by car’s computer? This is the first time I have encountered anything like this in regards to smog checks.

    1. Hi Mae,

      I’m sorry you’re having trouble completing monitors on your 2007 VW Rabbit. If it makes you feel better, VWs are known for presenting a bit of a challenge when it comes to running monitors.

      First, let’s clear something up “OBD Not Ready or Incomplete” is not an “error”. It simply means that your vehicle’s on board diagnostic system (“The Computer”) is still checking things out.

      Each test “The Computer” runs on itself and its related systems requires that certain enabling criteria are met before the test can be run. If a test fails, the check engine light is turned on; otherwise, the tests run in the background and we normally don’t have to give them a second thought.

      However, in your case, since your VW needs to pass a smog inspection, you’re in a position to give them a lot of thought.

      While most cars will complete readiness monitors within 50 to 100 miles of a computer reset, some cars may require more driving. This is especially true if a monitor (really just a test) is on the verge of failure, or enabling criteria are not being met.

      The following drive cycle is recommended for your your 2007 Volkswagen Rabbit :

      – Switch the ignition on and start the vehicle.
      – Idle the vehicle for 2-3 minutes. This executes the O2S Heater, Misfire, Secondary AIR, Fuel Trim, and Purge system monitors.
      – Drive the vehicle at 45-55 mph for a continuous 7 minute period, avoid stopping. This executes the EVAP, O2S, Fuel Trim, and Misfire monitors.
      – Accelerate the vehicle to an engine speed of 5000 RPM (with automatic transmission use the tip-tronic mode) lift off the throttle until the engine speed is around 1200 rpm. This executes the fuel cut off
      – Accelerate the vehicle smoothly to 60-65 mph, cruise constantly for 5 min, this executes the Catalyst, O2S, Misfire, Fuel Trim, and Purge System monitors.
      – Decelerate and idle the vehicle again for 3 minutes. This executes the Misfire, Secondary AIR, Fuel Trim, and Purge system monitors.

      You may have to repeat this process several times. If you have access to a scan tool or code reader (Even a Harbor Freight code reader will do the trick), you can check for monitor completion as you go.

      Since all of the above can be difficult to pull off during normal Southern California driving conditions, I usually recommend a nice Saturday or Sunday morning drive when traffic is more manageable.

      Safe driving

  26. Thank you, Julius. I took it to a smog check station again for the third time, and I got the same result, “Not Ready” on the printout. I decided I will wait another week to return it to the smog check station. I have already spent $51.75 for the first test, and another $26.75 for the retest. The check engine light did not come back on. If the monitor on my car is the problem, how much does it usually cost to get a replacement monitor? I hope I am understanding everything.

    1. Hi Mae,

      A monitor isn’t something that would go bad, or require replacement. Think of a monitor as a test, or process, in your car’s computer software that keeps an eye on (Monitors) your car’s emissions related systems and sensors. The monitor itself wouldn’t be the problem, instead it might help to take a look at the system or sensor being monitored. Does that make sense?

      Here’s what I would suggest:

      First try following the Drive cycle procedure I described in my previous reply. It often helps to let the car sit overnight before each attempt. That way the car is sure to perform a full cool down and warm up cycle.

      If the monitors do not run after several attempts at following the drive cycle (Remember that the cool down and warm up cycles are important), I would suggest taking the car to a mechanic that has experience working on Volkswagen. A good Volkswagen mechanic will have access to tools and diagnostic equipment that many shops wont.

      Have your mechanic check systems to the monitors that aren’t running. Very often one monitor (test) will be dependent on the results of another. For example the secondary air monitor may depend on the O2 sensor monitor. If the O2 sensor monitor isn’t running, your mechanic could check the O2 sensors, if the results are borderline correcting any O2 sensor related issues (Including exhaust leaks around the sensors) could be the key to getting the monitors to run. That’s just an example of how your mechanic could go about checking your vehicle. If the Secondary Air Monitor is the only one that isn’t running, he could check that system first.

      Again, performing the recommend drive cycle two or three times should hopefully do the trick. Let me know how it all works out.

  27. HI,
    My 2003 Mitsubishi Galant cannot be smogged because, they tell me, the OBD system in the car is not communicating with the smog-checking device. I took it in to check all electric wires; a loose one was fixed, and the dealership says the car can communicate. I then took it to smog-check–but the tech had the same problem as before, car cannot communicate with the CA state smog system.
    This is the third smog center that has tried to smog it. What more can I do to fix the OBD? Thanks.

    1. Hi Anne,

      That’s a tough question to answer without actually seeing the connector on the car, but my guess is that one of the terminals is just loose enough that it’s completing contact with the scan tool in your mechanics shop, but not quite good enough for the smog machine.

      The only think that I can suggest off the top of my head is that you have your mechanic double check the diagnostic link connector in your vehicle, and ensure that all the terminals are secure and firmly in place. Sorry that I couldn’t be more help.

  28. I took my 1997 infin i30. To the emmission in phx,Az..
    This vehicle has passed equipment expection and felt the emission test This vehicle has failed to communicate with the OBD emission testing equipment as per APA Guidance the vehicle fails the Arizona emissions OBD testing for no communication (OBD-ON BOARD DIAGNOSTIC OR VEHICLES COMPUTER)
    THEY CHECK ENG..LIGHT IS NOT ON…

    NEED HELP ON WHAT TO DO..

    1. Hi Corina, I’m not familiar with the smog check program in Arizona, but based on your comment I assume that you need to have the cause of the on board diagnostic communication failure repaired. If you don’t have a mechanic, perhaps the inspection station that conducted your emissions test could help you locate a shop in your area.

  29. I have a 2011 honda fit, took it for smog. Smog guy says the cat sensor is not ready, and to drive it around some more week later ovee a hundred miles still not ready. The drive cycle is impossible. Don’t know what to di

    1. Drive cycles can be challenging, but the one for your car shouldn’t be too bad. At least, I haven’t seen a lot of people having trouble with 2011 Honda Fits.

      I’d suggest a couple of things.

      First make sure that you’re letting the car warm up completely before you start the drive cycle. We’ll typically let them idle for ten minutes before we even get started.

      Second try running the drive cycle early on a Saturday or Sunday when traffic is light. The key to most if these drive cycles is even acceleration and steady cruise. Avoid unnecessary braking and acceleration.

      If the monitor just wont run to completion, a component or sensor on the verge of failure might be the problem. The good news is that many emissions related components may still be under warranty on your 2011 Fit.

      If you’re not too far from Huntington Beach, you can always bring the vehicle in to Just Smogs. We have great success diagnosing monitor issues and running monitors to completion. You can make an appointment at (714) 596-1019.

Leave a Reply