Diagnostic Aids
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Check for any of the following conditions:
- Check for a skewed or shifted FTP sensor.
- If a DTC P0451 is intermittent, driving vehicle under conditions outlined in Inspection/Maintenance System Information section can verify whether the fault is present. See INSPECTION/MAINTENANCE EVAP SYSTEM SET PROCEDURE under INSPECTION/MAINTENANCE PROCEDURES (DRIVE CYCLES).
- EVAP system diagnostic can be monitored on scan tool under I/M System Information selection. When EVAP test displays a YES status, indicating the system diagnostic is completed, check for DTC P0451 in LAST TEST FAILED screen of scan tool. If there is no DTC P0451 displayed, EVAP system diagnostic has run and passed, indicating no malfunction was present this time. DTCs MUST be cleared to view CURRENT STATUS of system diagnostics being performed. I/M System Information tests only indicate the test has run, not if test passed or failed. The LAST TEST FAILED screen must be checked for related DTCs to determine the outcome of the diagnostic test involved.
An intermittent malfunction may be caused by a fault in FTP sensor electrical circuit. Check wiring harness and components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. Repair any electrical circuit faults found. Information included in freeze frame data can be useful in determining vehicle operating conditions when DTC first set.