P0454
DTC P0451-P0454
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provide an overview of each diagnostic category.
DTC Descriptors
DTC P0451
- Fuel Tank Pressure Sensor Performance
DTC P0452
- Fuel Tank Pressure Sensor Circuit Low Voltage
DTC P0453
- Fuel Tank Pressure Sensor Circuit High Voltage
DTC P0454
- Fuel Tank Pressure Sensor Circuit Intermittent
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The fuel tank pressure sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The engine control module (ECM) supplies a 5 V reference and a low reference circuit to the fuel tank pressure sensor. The fuel tank pressure sensor signal voltage varies depending on EVAP system pressure or vacuum. The ECM also uses this fuel tank pressure sensor signal to determine atmospheric pressure for use in the small leak test, DTC P0442.
Conditions for Running the DTC
P0451
* This diagnostic runs when the engine off natural vacuum small leak test, DTC P0442, is in progress.
* This diagnostic can be tested 2 times during the engine off period.
P0452 and P0453
* The average fuel level is between 6-40 L (0-10 gal).
* DTCs P0452 and P0453 run continuously when the ignition is ON.
P0454
* This diagnostic runs when the engine off natural vacuum small leak test, DTC P0442, is in progress.
* This diagnostic can be tested 1 time during the engine off period.
* The ECM does not detect a refueling event.
Conditions for Setting the DTC
P0451
DTC P0451 will set if the controller is unable to re-zero the fuel tank pressure sensor voltage within a calibrated range. The length of the test can be up to 10 min.
P0452
The fuel tank pressure sensor voltage is less than 0.15 V for more than 0.1 s.
P0453
The fuel tank pressure sensor voltage is more than 4.85 V for more than 0.1 s.
P0454
The ECM detects an abrupt change in the fuel tank pressure sensor voltage, other than a refueling event. The length of the test can be up to 10 min.
Action Taken When the DTC Sets
P0451 or P0454
DTCs P0451 and P0454 are Type A DTCs.
P0452 or P0453
DTCs P0452 and P0453 are Type B DTCs.
Conditions for Clearing the DTC
P0451 or P0454
DTCs P0451 and P0454 are Type A DTCs.
P0452 or P0453
DTCs P0452 and P0453 are Type B DTCs.
Diagnostic Aids
* A restriction in the EVAP canister or vent lines may prevent fuel vapor pressure from bleeding off fast enough. If the vent system cannot bleed off pressure fast enough, the reset procedure may not complete successfully, which may cause this code to set.
* Ensure that the reference port on the fuel tank pressure sensor is unobstructed.
* Scan tool output controls, snapshot, and the plot function can help detect erratic sensor operation. To observe the fuel tank pressure sensor signal under vacuum conditions, use the quick snapshot and the EVAP purge/seal function to capture data while commanding purge to 20%. Then plot the data to look for erratic sensor operation. A similar test can be done for the pressure side of the sensor range by applying pressure with EN 41413-200 - Evaporative Emissions System Testerwhile taking a snapshot with the scan tool.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
EN 41413-200 - Evaporative Emissions System Tester
For equivalent regional tools, refer to Special Tools Tools and Equipment.
Circuit/System Verification
Note: The order of these steps is important. If not followed properly you will be bleeding off any pressure or vacuum in the system and not see any change in the ELDP sensor.
Note: Read the instructions for P0451 in their entirety before proceeding to understand what is being required.
Note: Ambient and vehicle component temperature must be above 0°C (32°F) to command the switching valve or vacuum pump. This prevents erroneous results and damage to the ELDP assembly.
P0451
1. Vehicle in Service Mode, whatever the FTP sensor parameter, pressure or vacuum, is showing on the scan tool, release it with the Venting command button under controls functions, EVAP Vent Solenoid Valve command. FTP sensor parameter should be 0.07 in. H2O, 0.01 kPa (0.00 PSI) after 5 s.
Note: There is a conversion button on the right hand side of the scan tool screen called Light Switch to toggle between kPa/Metric and PSI/English values.
2. Using the scan tool control functions, EVAP Test, command the ELDP pump on to get the FTP sensor parameter to -11.56 in. H2O, -2.88 kPa (-0.42 PSI) or greater. This may take several seconds.
Note: Use of any control function other than EVAP test will not create a vacuum in the system.
Note: Vacuum will decay exiting the EVAP test and going to step 3. This is normal. There should be sufficient vacuum left to perform steps 3 and 4.
3. Observe and note the ELDP and FTP sensor parameters with a scan tool. Note, reading one.
4. Perform the following steps in this order.
* Select scan tool Fuel Tank Pressure Sensor Test under control functions.
* Command the ELDP switching valve command to not venting by clicking the corresponding button.
* Wait for 3 seconds.
* Command the EVAP vent solenoid valve command ON by clicking the corresponding button.
Note: Wait for 15 s while observing the parameters then click the pause button on the scan tool to retain the parameters.
5. Observe and note the ELDP and FTP sensor parameters with a scan tool. Note, reading two. Press the Release Control button when the noted parameters are recorded.
Note: The subtraction results and FTP parameter should be negative since a vacuum was pulled on the system.
6. Subtract the ELDP reading 2 from ELDP reading 1. This value equals what the FTP sensor, reading two, should be (ELDP reading 2 - ELDP reading 1 = FTP reading 2). The FTP sensor should be within 3 in. H2O, 0.749 kPa (0.11 PSI) of the subtraction just performed.
• If not refer to diagnostics aids and perform circuit/system testing.
• If FTP sensor shows within 3 in. H2O, 0.749 kPa (0.11 PSI).
7. All OK.
P0452 and P0453
1. Request a refueling event. This opens the vent valve to bleed off any pressure or vacuum.
2. Remove the fuel cap.
3. Vehicle in Service Mode.
4. Observe the scan tool FTP sensor parameter. It should be 2.63 V at 0 kPa (0 PSI).
Circuit/System Testing
1. Vehicle OFF, disconnect the harness connector B150 fuel tank pressure sensor.
Note: Testing for steps 2-6 is performed on the ECM side of the harness connector.
2. Vehicle OFF, all systems OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 ohms between the B150 fuel tank pressure sensor low reference circuit terminal 2 and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
3. Vehicle in Service Mode, test for 4.8-5.2 V between the B150 fuel tank pressure sensor 5 V reference circuit terminal 3 and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
4. Verify the scan tool FTP sensor parameter is less than 0.2 V.
• If greater than the specified range, test the B150 fuel tank pressure sensor circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
5. Install a 3 A fused jumper wire between the B150 fuel tank pressure sensor signal circuit terminal 1 and the 5 V reference circuit terminal 3. Verify the scan tool FTP sensor parameter is greater than 4.7 V.
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
Note: Testing for this step is performed on the EVAP assembly side of the harness connector.
6. Remove the EVAP assembly and test, inspect, and repair the items listed below. If all items test normal, replace the B150 fuel tank pressure sensor.
* Poor connection at the X350 harness connector
* Open or shorted 5 V reference circuit
* Open or shorted sensor signal circuit
* Open low reference circuit
Repair Instructions
For DTC P0452 or P0453, perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* For DTC P0451 or P0454, clear DTCs with a scan tool.
* Control Module References Control Module References for ECM replacement, programming and setup