DTC will set. An abrupt change is defined as a change of 0.45 inch H2O in the span of 1 second.
Action Taken When the DTC Sets
* DTC P0451 and P0454 are Type A DTCs.
* DTC P0452 and P0453 are Type B DTCs.
Conditions for Clearing the MIL/DTC
* DTC P0451 and P0454 are Type A DTCs.
* DTC P0452 and P0453 are Type B DTCs.
Diagnostic Aids
P0451 and P0454
* A restriction in the EVAP canister or vent lines could prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot
bleed off pressure fast enough, the re-zero procedure may not complete successfully, which could cause this code to set.
* Ensure that the reference port on the FTP sensor is unobstructed.
* An FTP sensor that is skewed or does not have a linear transition from low to high may cause this code to set. Scan tool output controls,
snapshot, and plot functions can help detect erratic sensor response. To test the sensor signal under vacuum conditions, use the Quick
Snapshot and the Purge/Seal functions to capture data while commanding purge to 20 percent, then plot the data to look for erratic sensor
operation. A similar test can be done for the pressure side of the sensor operation by applying pressure with the J 41413-200 while taking a
snapshot.
Reference Information
Schematic Reference
Engine Controls Schematics (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Special Tools
J 41413-200 Evaporative Emission System Tester (EEST)
Circuit/System Verification
1. Remove the fuel cap.
2. Ignition ON, engine OFF.
3. Observe the Fuel Tank Pressure Sensor parameter with a scan tool.
4. The FTP Sensor parameter should be 1.3-1.7 V.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the FTP sensor.
2. Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohms of resistance between the low reference circuit
terminal 2 and ground.
锟斤拷If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
