|
Gas caps are usually attributed to a Large (Gross) Evap Leak, as someone stated above. Usually small leaks could be related to a bad hose or a solenoid that isn't opening or closing properly. A technician will be able to use a diagnostic tool to operate all the solenoids within the system to make sure they're activating/responding. Also they may run smoke through the system to check for visible leaks.
EVAP codes are the harder of the common CEL codes to diagnose, in my opinion.
If I'm repeating the comments of others, sorry. A lot of the EVAP codes in GM's that run through my shop are related to a faulty vent solenoid. I've even installed new ones that test bad as well.
|