What the inspection checks
California’s OBD inspection rule lists the conditions that fail a car. One of them is that the car’s OBD data doesn’t match the carmaker’s software or a version exempted by the California Air Resources Board (CARB) (BAR, 2019). BAR announced automated Cal ID and CVN checks at Smog Check stations for most 2000 and newer vehicles from July 2020 (BAR newsletter, spring 2020).
The Cal ID names the program on the engine computer, and the CVN is a code calculated from it. A modified program produces a different CVN (BAR). More on the two codes.
What the failure means: a CVN mismatch
BAR planned for the inspection report to give the cause as the CVN and Cal ID not matching a valid configuration (BAR). People call this a CVN mismatch. In plain terms: the software on the car isn’t the factory version and isn’t an approved aftermarket version.
How to pass
BAR’s answer is to restore the computer to stock or ARB-approved software (BAR). Some aftermarket software is legal in California through CARB’s Executive Order process (BAR). If the car came to you tuned and you don’t have the original file, a dealer can usually reprogram the engine computer with current factory software.
The other ways an OBD inspection fails
The same rule fails a car for other OBD reasons too (BAR), including:
- the check-engine light commanded on, or a stored fault code;
- the OBD system not having run long enough to tell whether there are faults;
- unfinished readiness monitors: for gasoline cars from 2000 on, any unfinished monitor except the evaporative system; for diesels from 2007 on, any except the particulate filter.
Before you buy a car in California
Our check reads the same Cal ID and CVN, plus the warning light, fault codes and readiness monitors. One difference: we compare with other cars that have been checked, not with BAR’s list, so a result here can’t promise a pass. A car that shows signs of changed software here is one to ask hard questions about.