B0478

DTC B0465, B0467, or B0478

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B0465 00
- Auxiliary Heater Flame Sensor Circuit Low

DTC B0467 00
- Auxiliary Heater Flame Sensor Circuit Open

DTC B0478 00
- Flame Off for minimum power

Diagnostic Fault Information







Circuit/System Description

The fuel operated heater uses a coolant heater combustion sensor to monitor flame temperature.

Conditions for Running the DTC

Engine is running.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

Fuel operated heater is disabled.

Conditions for Clearing the DTC

DTC must be cleared with a scan tool.

Circuit/System Verification

Start the vehicle. Observe the coolant heater combustion sensor scan tool parameter. The scan tool parameter should display between 0.09-4.9 volts.

Component Testing

1. Ignition OFF, disconnect the 14 pin coolant heater module connector from the module.
2. Test the coolant heater combustion sensor resistance.
3. Compare the readings with the Temperature vs Resistance table and verify that the resistance is within 5 percent of the specification.

• If the resistance vs temperature reading is not within 5 percent, replace the coolant heater sensor.

4. If the coolant heater combustion sensor tests normal, replace the coolant heater.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Heater Coolant Heater Glow Plug Replacement
* Heater Coolant Heater Replacement Verification Tests