Service Engine Soon Light Illuminated And DTC P0411 - keywords 3.5 air code detected ECM flow incorrect injection LZ4 MIL PCM pump relay secondary SES

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment that the Service Engine Soon light is illuminated. When checking for Diagnostic Trouble Codes (DTC) in the Powertrain Control Module (PCM), Diagnostic Trouble Code P0411 (Secondary Air Injection (AIR) System Incorrect Air Flow Detected) may be found.

Please be advised that new diagnostic procedures became available in SI beginning in late March 2008 to address this issue.

Make sure you are using the new procedures before beginning your diagnosis.

If the diagnostics lead you to replace the relay that controls the Secondary Air Injection "Pump" (located in the underhood electrical center (not the relay that controls the pump solenoid)) replace the relay as necessary

If the diagnostic DOES repair the vehicle, then contact Jim Kelly on (586) 492-5612. He will supply you with a parts waiver and information on where to send the old relay to.

If the diagnostic Does NOT repair the vehicle, then contact Jim Kelly on (586) 492-5612 and he will make arrangements for someone from GM Powertrain Engineering to contact you as soon as possible.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.