EVAP Control System Diagnostic Procedure

The enhanced Evaporative System Diagnostic is a precise series of eight operational subtests on the system. In some cases, the failure of only one subtest will end all evaporative system testing; however, in many cases, the on-board system will conduct a series of subtests before storing any DTCs.

The diagnostic codes associated with the system include DTC PO440, PO442, PO446, PO452, PO453, and PO144. Refer to FAULT ISOLATION article.