Diagnostic Aids
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- If DTC P0440, P0442, P0446, or P0455 is set, EVAP special functions on the scan tool will not be allowed. Clear DTCs before performing these tests.
- The ECM uses the FTP sensor to detect the pressure of fuel vapor in the fuel tank during all parts of the EVAP diagnostic system test. Ensure the FTP sensor is not skewed by verifying FTP sensor on the scan tool is 1.3-1.7 volts with the ignition on and engine off.
- The following are possible causes of a large EVAP leak:
- fuel cap is missing, incorrectly installed or leaking.
- EVAP vent solenoid valve stuck open.
- EVAP purge solenoid stuck closed/blocked or lack of manifold vacuum to solenoid.
- EVAP line/hose connections are disconnected/leaking.
- The fuel sender O-ring is leaking.
- FTP sensor seal is leaking.
- To help locate intermittent leaks, use the Evaporative Emission System Tester (J-41413-200) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the High Intensity White Light (J-41413-SPT).
- To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J-41413-SPT.
- Review the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to set occurs. This may assist in diagnosing the condition.
- For intermittent conditions, refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L & 3.0L VUE article.