Monitor DTC Status

CAUTION: If DTCs (or pending codes) relating to FTPS are present, do ALL REPAIRS associated with those codes before proceeding with this troubleshooting tree.

Start the engine and allow it to reach normal operating temperature.
CAUTION: Evaporative Emissions Systems (EVAP) Leak Tests can be run by the Scan Tool. The tests are automated and provide either a pass-fail result or directions to check for DTCs.
Install scan tool and clear DTC
Perform "EVAP. LEAKAGE TEST" mode referring to the following enable conditions:
1. Engine at idle (Engine RPM should not change during the test)
2. No relevant DTC & All accessories should be turned OFF during the test
3. Fuel level is below 80%
  
  Fig 1: Display Sample Screen Of EVAP Leak Test
Is DTC P0451 stored?
YES
1. Go to "W/HARNESS INSPECTION " procedure
NO
1. Fault is intermittent, caused by poor contact in the sensor's and/or ECM's connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure