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2004 GMC Safari with OBD-II Codes P0455 and P0449: Diagnosis and Fixes

Model: 2004 GMC Safari Fault Code: P0449 Posted: 2012-06-12 16:54

My 2004 GMC Safari has been displaying OBD-II trouble codes P0455 and P0449. I took it to a Pep Boys shop, where they suggested one of three potential causes: the gas canister purge valve, the vent solenoid, or a faulty gas cap. I replaced all three components, and the check engine light stayed off for one day before returning. The same codes reappeared. Any additional troubleshooting steps or diagnostic advice would be greatly appreciated.

Related fault codes
P0449P0455
Comments (2)
Anonymous 2012-06-13 04:56

Don't rely solely on Pep Boys' diagnosis—verify each component and its associated wiring circuits. Check the fuses and inspect the harness connections leading to the purge valve and vent solenoid.

Anonymous 2012-06-13 07:46

This issue should be flagged as a sticky post. There is no OBD-II code that directly instructs you to replace a part. After replacing the vent solenoid, did you verify 12 volts at the harness connector? Was the vent hose securely connected at both ends with no visible cracks? Specifically: Pink wire should have 12V when the key is on; white wire must be intact and not open when the key is off.