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 P0452: Fuel Tank Pressure (FTP) Sensor Circuit Low Voltage
DTC P0453: Fuel Tank Pressure (FTP) Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
FTP Sensor Low Reference | -- | P0446, P0451 | P0446 | -- | P0451 |
FTP Sensor Signal | P0452 | P0451 | P0452 | P0453 | P0451 |
FTP Sensor 5-Volt Reference | P0452, P0530, P0641 | P0451 | P0446, P0452 | P0453, P0530, P0641 | -- |
Typical Scan Tool Data
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
|---|---|---|---|---|
Operating Conditions: With EVAP system vented to atmosphere | ||||
FTP Sensor Low Reference | -- | 1.5 V | 4.6 V | -- |
FTP Sensor Signal | 1.5 V | 0 V | 0 V | 5 V |
FTP Sensor 5-Volt Reference | -- | 0 V | 0 V | 5 V |
Circuit/System Description
The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The control module supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The control module also uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed. The sensor performance test includes checks for sudden changes in pressure or signal oscillation and a pressure range check.
This turbocharged engine is equipped with a one way flow check valve that prevents boost pressure form entering the purge line and EVAP system.
Conditions for Running the DTC
P0451
| • | The engine is running. |
| • | The estimated ambient air temperature is greater than -7°C (+19.4°F). |
| • | The EVAP canister vent valve has been open for more than 3 seconds. |
| • | The vehicle speed is less than 29 km/h (18 mph) for the signal oscillation test or greater than 0 km/h (0 mph) for the signal range test. |
P0452 and P0453
| • | The engine is running. |
| • | The vehicle speed is 0 km/h (0 mph). |
| • | The ambient pressure is greater than 68 kPa. |
| • | The estimated ambient air temperature is greater than -7°C (+19.4°F). |
| • | The fuel level is between 12-88 percent. |
| • | DTC P0452 and P0453 run continuously when the above conditions have been met. |
Conditions for Setting the DTC
P0451
| • | There is a sudden change in fuel tank pressure greater than a calibrated amount for up to 50 seconds. |
| OR |
| • | The FTP is greater than 7 in H2O or less than -16 in H2O for more than 14 seconds. |
P0452
The FTP sensor voltage is less than 0.1 volt for more than 14 seconds.
P0453
The FTP sensor voltage is more than 4.9 volts for more than 14 seconds.
Action Taken When the DTC Sets
DTCs P0451, P0452 and P0453 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0451, P0452 and P0453 are Type B DTCs.
Diagnostic Aids
P0451
| • | 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 (J 41413-100) while taking a snapshot. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Special Tools Required
J 41413-200 (J 41413-100) Evaporative Emission System Tester (EEST)
Circuit/System Verification
Ignition ON, observe the scan tool fuel tank pressure (FTP) sensor parameter. The reading should be between 1.3-1.7 volts with the fuel cap removed, and change with fuel tank pressure.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the FTP sensor.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.
- Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.
- Verify the scan tool FTP sensor parameter is less than 0.1 volts.
- Install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool FTP sensor parameter is greater than 4.7 volts.
- If all circuits test normal, test or replace the FTP sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module. |
| ⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the control module. |
| ⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the control module. |
| ⇒ | If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the control module. |
| ⇒ | If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module (ECM) replacement, setup, and programming |
