Diagnostic Procedures

Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
Is a DTC P2027 also set? If yes, go to step 7 . If no, go to next step.
Turn ignition off. Remove fuel filler cap. Turn ignition on, with engine off. Select the FTP sensor parameter on the scan tool. Is the pressure within 0.0-0.5 in. H2O (0.0-0.9 mm Hg)? If yes, go to step 12 . If no, go to next step.
Remove fuel tank. Remove FTP sensor from the fuel tank. Visually inspect the sensor orifice and the air pressure inlet passage for clogging. Clean the FTP sensor orifice and inlet passage as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to next step.
Turn ignition off. Disconnect the FTP sensor electrical connector. Turn ignition on, with engine off. Measure the voltage of the 5-volt reference circuit with a DVOM connected to ground. Is the voltage at 5.0 V? If yes, go to step 7 . If no, go to next step.
Test for high resistance in the 5-volt reference circuit between the FTP sensor and the PCM. Repair as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to step 13 .
Connect a test light between the ground circuit of the FTP sensor and battery voltage. Does the test light illuminate? If yes, go to step 9 . If no, go to next step.
Test for an open or high resistance in the FTP sensor ground circuit. Repair as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to step 13 .
Turn ignition off. Connect the FTP sensor electrical connector. Backprobe the FTP sensor input circuit at the PCM with a DVOM connected to ground. Turn ignition on, with engine off. Measure the voltage with the DVOM set to the DC scale. Is the voltage within 2.5-2.7 V? If yes, go to next step. If no, go to step 11 .
Apply a small amount of vacuum to the FTP sensor while observing the DVOM. Does the voltage decrease when the vacuum is applied? If yes, go to next step. If no, go to step 15 .
Test the FTP sensor input circuit for high resistance or short to voltage. Repair as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to step 15 .
Inspect the EVAP system for the following conditions: Test the FTP control valve for proper operation. Inspect for a stuck closed or blocked EVAP canister vent valve. Inspect the vapor lines and hoses between the EVAP canister and the fuel tank for restrictions or blockage. Repair or replace the component as necessary. Did you find and correct a condition? If yes, go to step 16 . If no, go to DIAGNOSTIC AIDS .
Inspect the PCM and the Manifold Absolute Pressure (MAP) sensor electrical connectors for faulty terminal contact. Repair as necessary. Did you find and correct condition? If yes, go to step 16 . If no, go to next step.
Turn ignition off. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After replacing PCM, go to next step.
Replace the FTP sensor. After repairs, go to next step.
Turn ignition off. Remove DOME fuse for 30 seconds. Install DOME fuse. Reset radio clock time. Start engine. Operate vehicle within the Freeze Frame conditions that set the DTC or until the DTC P0451 diagnostic test has run. Does the DTC run and pass? If yes, go to next step. If no, go to step 2 .
With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? DIAGNOSTIC TROUBLE CODE DEFINITIONS