California DMV requires a smog check for the following reasons:
- Biennial Inspection
The most common reasons a vehicle is required to be smog certified is simply to comply with California biennial (every other year) smog check regulations. Once a gasoline vehicle is older that 8 years, the DMV requires a passing smog check every other year. So for example in 2021, vehicle model years 2013 and older will require a smog check. Vehicle model years 1975 and older are exempt from inspection.
Diesel vehicles do not get the 8 year waiver. All 1998 and newer diesel vehicles under 14,000 GVWR are required to be inspected every other year.
- Transfer of Ownership
A smog check certification is required when a vehicle is 6 model years or older gets sold in California. The seller of the vehicle is required to provide a passing smog check certificate (within 90 days) upon time of sale.
- Out of State Transfer
When a vehicle is brought into California from another state, a smog check is required regardless of how new the vehicle is. 1975 and older gasoline vehicles and 1997 and older diesel vehicles are exempt.
- Salvage Title
California can require a smog check and brake-and-lamp inspection if a vehicle becomes titled salvaged.