Check OBD II Monitor Readiness Without A Scan Tool

Image of instrument cluster including "Check Engine" lightIt is possible to check OBD II monitor readiness on many late model vehicles without connecting a scan tool. This can often be necessary in order to determine if your car is ready for its California smog inspection.

What is OBD II monitor readiness?

On 1996 and newer model year vehicles, the on board diagnostic system (OBDII) performs up to eleven diagnostic checks of vehicle emission control systems.  These checks are performed in the background during normal driving and are designed not to interfere with vehicle performance or safety.

If a fault is detected, the power train control module (PCM – The computer) illuminates the malfunction indicator light (MIL – Check Engine – Service Vehicle Soon).

If the PCM loses power for any reason (Including a disconnected or depleted battery), or if diagnostic trouble codes are cleared using a diagnostic scan tool, readiness monitors will indicate an incomplete, or not ready, status.

In most cases, a vehicle with incomplete readiness monitors will not pass the California smog inspection (See New Readiness Monitor Standards For OBD II Functional Inspection).

Driving the vehicle under conditions that meet the monitor enabling criteria should complete most OBD II monitors.  This is usually accomplished after fifty to one-hundred miles of normal driving.

How to check monitors without a scan tool

In most cases, the correct procedure is outlined in your vehicle’s owner’s manual. Consult your owner’s manual for information specific to the car you drive.

However, the following procedures are presented as examples. They may not apply to your specific vehicle.

Ford/Lincoln/Mercury Vehicles

To determine if readiness OBD II monitors are complete:

  1. Turn the ignition key to the “on” position for 15 seconds without cranking the engine.
  2. If the “Service Engine Soon” light blinks eight times, one or more readiness monitors are incomplete.
  3. If the service engine soon indicator stays on solid, all readiness monitors are complete.

This procedure was included in the Owner’s Manual for a 2012 Ford Focus. This same procedure may apply to other models and model year Ford/Lincoln/Mercury vehicles.

For Jeep, Chrysler and Dodge

The owner’s manual states that the vehicle has a simple ignition key actuated test, which you can use prior to going to the test station. To check if your vehicle’s OBD II system is ready, you must do the following:

  1. Turn the ignition switch to the “ON” position, but do not crank or start the engine. If you crank or start the engine, you will have to start this test over.
  2. As soon as you turn the ignition switch to the ON position, you will see the MIL (Check Engine Light) symbol come on as part of a normal bulb check.
  3. Approximately 15 seconds later, one of two things will happen:
    1. The MIL will flash for about 10 seconds and then return to being fully illuminated until you turn OFF the ignition or start the engine. This means that your vehicle’s OBD II system is not ready and you should not proceed to the smog check station.
    2. The MIL will not flash at all and will remain fully illuminated until you turn OFF the ignition or start the engine. This means that your vehicle’s OBD II system is ready and you can proceed to the smog check station.
Honda/Acura

To check if the readiness codes are set, turn the ignition switch to the ON (II) position, without starting the engine. The MIL will come on for 20 seconds. If it then goes off, the readiness monitors are set. If it blinks five times, the readiness monitors are not set.

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