Diagnostic Aids

Although this DTC is considered a type A diagnostic (refer to "Engine Control Module"), it acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.

Check for the following conditions:

1. Missing or damaged O-rings at fuel vapor and EVAP emission purge line canister fittings.
2. Cracked or punctured EVAP emission canister.
3. Damaged source vacuum line, EVAP emission purge line, EVAP emission vent hose or fuel tank vapor line.
4. Poor connection at ECM. Inspect harness connectors for the following conditions:
   • Backed-out terminals
   • Improper mating
   • Broken locks
   • Improperly formed
   • Damaged terminals
   • Poor terminal-to-wire connection