Diagnostic Aids

Although this DTC is considered a type A diagnostic, 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:

• Missing or damaged fuel cap
• Missing or damaged O-rings at fuel vapor and EVAP emission purge line canister fittings
• Cracked or punctured EVAP emission canister
• Damaged source vacuum line, EVAP emission purge line, EVAP emission vent hose or fuel tank vapor line
• 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
• Damaged harness. Inspect the wiring harness to the EVAP emission vent solenoid, EVAP emission canister purge valve and the fuel tank pressure sensor for an intermittent open or short circuit.
• Kinked, pinched or plugged vacuum source, EVAP emission purge or fuel tank vapor line. Verify that the line are not restricted.