• 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.

The fuel tank pressure sensor measures vapor 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 controller also uses this fuel tank pressure 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.

• DTC P0451 runs only when the engine-off natural vacuum small leak test, P0442, executes.
• The number of times this test runs can range from 0–2 per engine-off period. The length of the test can be up to 10 min.

DTC P0452 and P0453 run continuously when the ignition is ON.

• DTC P0454 runs only when the engine-off natural vacuum small leak test, P0442, executes.
• This test can run once per engine-off period. The length of the test can be up to 10 min.
• A refueling event is not detected. A refueling event is confirmed if the fuel level has a persistent change of 10% for 30 s during a 10 min refueling rationality test.

This DTC will set if the controller is unable to re-zero the fuel tank pressure sensor voltage within a calibrated range during the engine-off small leak test, P0442.

The fuel tank pressure sensor voltage is less than 0.15 V for greater than 10 s.

The fuel tank pressure sensor voltage is greater than 4.9 V for greater than 10 s.

If, during the engine-off natural vacuum small leak test, P0442, the ECM detects an abrupt fuel tank pressure signal change, other than a refueling event, this DTC will set. An abrupt change is defined as a change of greater than 0.45 in H2O (0.11 kPa) in the span of 1 s but less than 1 in H2O (0.25 kPa) in 12.5 ms. This test must fail twice to set this DTC.

• DTCs P0451 and P0454 are Type A DTCs.
• DTCs P0452 and P0453 are Type B DTCs.

• DTCs P0451 and P0454 are Type A DTCs.
• DTCs P0452 and P0453 are Type B DTCs.

• 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 DTC to set.
• Ensure that the reference port on the fuel tank pressure sensor is unobstructed.
• A fuel tank pressure sensor that is skewed or does not have a linear transition from low to high may cause this DTC to set. Scan tool control functions, 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%, 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 GE-41413-A while taking a snapshot.

Engine Controls Schematics

Master Electrical Component List

Evaporative Emission Control System Description

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Control Module References for scan tool information

• GE-41413-A Evaporative Emission System Tester
• GE-41415-60 Engine Induction System Leak Test Adapter/Capless Fuel Fill Adapter

For equivalent regional tools, refer to Special Tools.

1. Ignition ON.
2. Verify DTC P0641, P0651, P0697, P06A3, or P06D2 is not set.
• If any of the DTCs are set

  Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

• If none of the DTCs are set
3. Remove the fuel cap or install GE-41415-60 for capless fuel fill, if equipped.
4. Ignition ON, engine OFF.
5. Verify the scan tool Fuel Tank Pressure sensor parameter is between 1.3 and 1.7 V.
• If not between 1.3–1.7 V

  Refer to Circuit/System Testing.

• If between 1.3–1.7 V
6. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
7. Verify the DTC does not set.
• If the DTC sets

  Refer to Circuit/System Testing.

• If the DTC does not set
8. All OK.

1. Ignition OFF, all vehicle systems OFF, this may take up to 2 min, for all vehicle systems to power down. Disconnect the harness connector at the B150 Fuel Tank Pressure Sensor.
2. Test for less than 5 Ω of resistance between the low reference circuit terminal 2 and ground.
• If 5 Ω or greater
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K20 Engine Control Module.
• If less than 5 Ω
3. Ignition ON.
4. Test for 4.8–5.2 V between the 5 V reference circuit terminal 3 and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the 5 V reference circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 Ω in the 5 V reference circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K20 Engine Control Module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.
• If between 4.8–5.2 V
5. Verify the scan tool Fuel Tank Pressure parameter is less than 0.2 V.
• If 0.2 V or greater
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 1 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.
• If less than 0.2 V
6. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 3.
7. Verify the scan tool Fuel Tank Pressure sensor parameter is greater than 4.7 V.
• If 4.7 V or less
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the K20 Engine Control Module.
• If greater than 4.7 V
8. Test or replace the B150 Fuel Tank Pressure Sensor.

Perform the Diagnostic Repair Verification after completing the repair.

• Control Module References for control module replacement, programming and setup