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DTC P0452 or P0453 (LAU or LBW)

DTC P0452 or P0453 (LAU or LBW)

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 P0452

Fuel Tank Pressure Sensor Circuit Low Voltage

DTC P0453

Fuel Tank Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
5 V Reference

P0122, P0452, P0642

P0452, P0641

P0453, P0643

P0641, P0642, P0643

FTP Sensor Signal

P0452

P0452

P0453

-

Low Reference

-

P0446

-

-



Typical Scan Tool Data

FTP Sensor

Circuit Short to Ground Open Short to Voltage
Operating Conditions: Engine idling with closed loop control

Parameter Normal Range: 0.2-4.8 V

5 V Reference

0 V

0 V

5 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 ECM supplies a 5 V reference and a low reference circuit to the FTP sensor.

FTP Sensor Signal Voltage Fuel Tank Pressure
High, Approximately 1.5 V or More

Negative Pressure/Vacuum

Low, Approximately 1.5 V or Less

Positive Pressure



Conditions for Running the DTC


The engine speed is greater that 240 RPM.

The DTCs run continuously when the above condition is met for 105 Vs.


Conditions for Setting the DTC

P0452

The ECM detects the FTP sensor signal voltage is less than 0.2 V for 4 s, or a cumulative of 30 s.

P0453

The ECM detects the FTP sensor signal voltage is greater than 4.85 V for 4 s, or a cumulative of 30 s.

Action Taken When the DTC Sets

DTCs P0452 and P0453 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0452 and P0453 are Type B DTCs.

Diagnostic Aids

If a shared 5 V reference circuit is shorted to ground or shorted to a voltage, other 5 V reference circuits may be affected.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference


Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs


DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification


1. Ignition ON, check the diagnostic trouble code (DTC) information with a scan tool. DTCs P0641, P0642 or P0643 should not set.

2. If a DTC is set, refer to DTC P0641-P0643, P0651-P0653 or P0697-P0699 ECM

3. Observe the FTP Sensor voltage parameter. The FTP sensor voltage should be between 0.2-4.8 V.

4. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.


Circuit/System Testing


1. Ignition OFF, remove the fuse that supplies B+ to terminal 56-X2 of the K20 ECM.

2. Disconnect the multi-way harness connector X10, located near the fuel tank.

3. Test for less than 5 Ω between the low reference circuit terminal F and ground.

4. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.

5. Install the fuse that supplies B+ to terminal 56-X2 of the K20 ECM.

6. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal D and ground.

7. If less than the specified range, test the 5 V reference circuit for a short to ground or open/high resistance. If the circuit/connections test normal, replace the K20 ECM.

8. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit/connections test normal, replace the K20 ECM.

9. Observe the scan tool B150 FTP sensor parameter. Verify that the FTP Sensor parameter is less than 4.8 V.

10. If greater than the specified value, test the signal circuit terminal E for a short to voltage. If the circuit/connections test normal, replace the K20 ECM.

11. Install a 3 A fused jumper wire between the signal circuit terminal E and the 5 V reference circuit terminal D. Verify that the scan tool FTP Sensor parameter is greater than 4.8 V.

12. If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.

13. Remove the fuel tank. Refer to Fuel Tank Replacement .

14. Disconnect the B150 FTP sensor connector.

15. Inspect the FTP sensor circuits in the fuel tank harness, between the FTP sensor connector and X10 for the following conditions, and repair as necessary:

Damaged wiring or terminals

Open circuits

Short to Ground

Wire to wire short

16. If all circuits/connections test normal, test or replace the B150 FTP sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Fuel Pressure Sensor Replacement

Control Module References for ECM replacement, setup, and programming