Originally Posted by ryan1428
what is an EVAP system? How do I check it.
EVAP system basically keeps fuel vapors in containment, preventing from going into the atmosphere. There is a routine run randomly by the PCM or ECU that checks the integrity of the EVAP system by pulling vacuum on the system. If you do not have any EVAP system DTC's present, then in theory you haven't a problem with EVAP.