QuestionMy truck did not pass inspection b/c the check engine light stays on. The diagnostics shows that nothing is wrong. My mechanic reset the computer but the inspector says that the computer has to reset itself before it will pass. How long does this take? and what does it mean?
AnswerHi Debbie -
Are you telling me that the mechanic did not pull a diagnostic code from the engine light being on? Usually they connect an OBD (On Board Diagnostic) and it reads the code from the computer. If the light is on, there must be some sensor that is causing it, which would show up in the OBD.
As far as the reset, Usually (assuming there are no codes), the reset occurs almost immediately.
In summary, if the CEL (Check Engine Light) is on, then there has to be some code that is causing it. There are literally hundreds of codes, and many sensors in any combination. The OBD is an important part of the repair process, as it will fine tune where to start. Once the issue is repaired, and the computer senses there is not a problem anymore, the code will reset and the CEL should turn off.
The first step is to get back to your mechanic and ask him what the OBD code was, and then we can start from there. Ensure he is using the correct OBD for the vehicle, and he has the right software installed.
Hope this helps -
aloha
calvin
