B0455

DTC B0455 or B0457

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)provides an overview of each diagnostic category.

DTC Descriptors
DTC B0455 00
- Auxiliary Heater Coolant Sensor Circuit Low

DTC B0457 00
- Auxiliary Heater Coolant Sensor Circuit Open

Diagnostic Fault Information





Circuit/System Description

The fuel operated heater uses an auxiliary heater coolant sensor to measure the coolant temperature.

Conditions for Running the DTC

Engine is running.

Conditions for Setting the DTC

The fuel operated heater has recognized out of range condition for more than 2.5 seconds.

Action Taken When the DTC Sets

The fuel operated coolant heater is disabled.

Conditions for Clearing the DTC

* A current DTC will clear when the conditions for setting the DTC are no longer present.
* A history DTC will clear after 40 malfunction-free ignition cycles.

Reference Information
Schematic Reference

HVAC Schematics ()
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Air Temperature Description and Operation (Air Temperature)
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)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

Engine running, observe the scan tool Coolant Temp. Sensor parameter. The parameter should be between 0.09-4.9 volts.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the coolant heater temperature sensor.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit 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 coolant heater.

3. Ignition ON, verify the scan tool Coolant Temp. Sensor parameter is greater than 4.5 volts.

• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the coolant heater.

4. Install a 3A fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool Coolant Temp. Sensor parameter is less than 0.5 volts.

• If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the coolant heater.

5. If all circuits test normal, test or replace the coolant temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Heater Coolant Heater Air Temperature Sensor Replacement (Heater Coolant Heater Air Temperature Sensor Replacement)
* Heater Coolant Heater Replacement (Heater Coolant Heater Replacement)