Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0451: Fuel Tank Pressure (FTP) Sensor PerformanceDTC P0454: Fuel Tank Pressure (FTP) Sensor Intermittent
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop at idle Parameter Normal Range: 0.2-4.8 V | |||
5-Volt Reference Voltage | 0 V | 0 V | 0.7 V |
FTP Sensor Signal | 0 V | 0 V | 5 V |
Low Reference | -- | 4.2 V | -- |
Circuit/System Description
The evaporative emission (EVAP) system is used to store fuel vapors in order to reduce the amount of fuel vapors into the atmosphere. The fuel tank pressure (FTP) sensor is only used for EVAP system diagnostics. The FTP sensor is a transducer that varies resistance according to changes in the fuel tank pressure. The engine control module (ECM) monitors the FTP sensor signal in order to detect vacuum decay and excess vacuum during the EVAP system diagnostic test.
The following table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.
FTP Sensor Signal Voltage | Fuel Tank Pressure |
|---|---|
High, Approximately 1.5 Volts or More | Negative Pressure/Vacuum |
Low, Approximately 1.5 Volts or Less | Positive Pressure |
Conditions for Running the DTC
| • | The engine is running. |
| • | DTCs P0451 and P0454 run once an ignition cycle when the above condition is met. |
Conditions for Setting the DTC
P0451
The ECM detects the FTP sensor voltage is less than 0.58 volt within 13 seconds after start up.
P0454
The ECM detects an abrupt change in the FTP sensor voltage.
Action Taken When the DTC Sets
DTC P0451 and P0454 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTC P0451 and P0454 are Type B DTCs.
Diagnostic Aids
If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.
Reference Information
Schematic Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Special Tools
| • | J 41413-200 Evaporative Emissions System Tester (EEST) |
| • | GE-41415-50 Fuel Tank Cap Adapter |
| • | J 41413-300 EVAP Cap and Plug Kit |
Circuit/System Testing
- If DTC P0454 is set Inspect for an intermittent and for a poor connection at the FTP sensor and the engine control module (ECM).
- Remove the fuel fill cap. Connect the GE-41415-50 to the fuel tank filler neck. Connect the J 41413-200 to the GE-41415-50 .
- Disconnect the EVAP vent line from the vent solenoid, and seal it, using the correct plug from the J 41413-300 .
- Pressurize the EVAP system with nitrogen to 5 inches H2O. Compare the Fuel Tank Pressure Sensor parameter with a scan tool to the J 41413-200 pressure/vacuum gage. The scan tool FTP sensor parameter should be within 1 inch H2O of the pressure/vacuum gage.
- Command the purge solenoid valve OPEN with a scan tool.
Important: The EVAP vent solenoid valve will not remain closed when commanded ON with positive pressure applied to the EVAP system.
| ⇒ | If the FTP sensor parameter is not within 1 inch H2O of the pressure/vacuum gage, replace the FTP sensor. |
| ⇒ | If the FTP sensor parameter is not 0 inch H2O, replace the FTP sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
