Auxiliary Heater Fuel Pump Circuit Open
The B2452 code indicates that the Auxiliary Heater Control Module (AHCM) or the vehicle's control module has detected an open circuit in the electrical circuit of the auxiliary heater fuel pump. This system, commonly found in vehicles with a fuel-fired parking heater, operates independently of the main engine to warm the coolant or cabin. An open circuit means there is a break in power supply or continuity to the pump, preventing fuel delivery to the auxiliary heater burner. The controller typically monitors circuit voltage or resistance; if the value exceeds calibrated thresholds for an open circuit, the DTC is set and the auxiliary heating system is disabled to prevent improper operation.
1. Commonly Affected Makes
2. Most Common Causes
- Broken, disconnected, or corroded wiring in the auxiliary heater fuel pump circuit
- Blown fuse dedicated to the auxiliary heater circuit
- Auxiliary heater fuel pump with internal open circuit or damaged winding
- Faulty auxiliary heater fuel pump control relay (if applicable)
- Poor ground connection or corroded ground point in the pump circuit
- Auxiliary Heater Control Module (AHCM) with internal detection or control failure
3. Symptoms You Will Notice
- Auxiliary heater does not operate or produces no heat
- Check Engine Light or service heater warning illuminated
4. Step-by-Step Diagnosis
Scan for DTCs and verify B2452 is present
Inspect the auxiliary heater fuel pump fuse and replace if blown
Check wiring and connectors for damage, corrosion, or loose connections
Test the fuel pump relay (if equipped) for proper operation
Measure resistance and voltage at the fuel pump connector to identify open circuit
If all else is good, test the AHCM or replace as needed
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the auxiliary heater will not work, which may affect cabin comfort in cold weather.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause (e.g., fuse, wiring repair, or pump replacement).