Diagnostic Procedures
- Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Is DTC P0452 or P0453 also set? If yes, see DTC P0452: FUEL TANK PRESSURE SENSOR - LOW VOLTAGE or DTC P0453: FUEL TANK PRESSURE SENSOR - HIGH VOLTAGE . If no, go to next step.
- With a scan tool, seal the EVAP system. Start the engine. Increase the engine idle to 1200-1500 RPM. Observe the FTP sensor with a scan tool. Is the FTP sensor near 0 in. Hg (0 in. H2O)? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
- Turn the ignition OFF. Disconnect the EVAP canister purge valve harness connector. Remove and then install the fuel fill cap. With a scan tool, seal the EVAP system. Start the engine. Increase the engine idle to 1200-1500 RPM. Observe the FTP sensor with a scan tool. Is the FTP sensor near 0 in. Hg (0 in. H2O)? If yes, go to step 7 . If no, go to next step.
- Turn ON the ignition, with the engine OFF. Connect a test lamp between the control circuit and the ignition voltage circuit of the EVAP purge valve harness connector. Does the test lamp illuminate? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
- Test the purge valve control circuit for a short to ground. Did you find and correct the condition? If yes, go to step 10 . If no, go to step 8 .
- Replace the EVAP canister purge valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 10 .
- Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step 10 . If no, go to next step.
- Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Connect all EVAP hardware that was previously disconnected. Use a scan tool to seal the EVAP system. Start the engine and idle at 1200-1500 RPM. Observe the Fuel Tank Pressure (FTP) with a scan tool. Is the fuel tank pressure near 0 in. Hg (0 in. H2O)? If yes, go to next step. If no, go to step 3 .
- Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
NOTE:
Check for carbon release into the EVAP system. If carbon is present, see EVAPORATIVE EMISSION SYSTEM CLEANING in REMOVAL, OVERHAUL & INSTALLATION.