Auxiliary Heater Glow Plug Circuit Open
The Auxiliary Heater Control Module (AHCM) has detected an open circuit in the glow plug circuit of the parking or auxiliary heater. This prevents the glow plug from generating the heat needed for fuel ignition in the heater's combustion chamber, disabling the heater.
1. Commonly Affected Makes
2. Most Common Causes
- Damaged auxiliary heater glow plug or internal open circuit
- Open, cut, or corroded wiring in the glow plug circuit
- Loose, oxidized, or retracted terminals in the heater harness connectors
- Internal failure of the Auxiliary Heater Control Module (AHCM)
3. Symptoms You Will Notice
- Auxiliary heater does not operate or fails to start
- Check engine light or heater warning light illuminated
4. Step-by-Step Diagnosis
Scan for codes and verify B2450 is present
Visually inspect glow plug wiring and connectors for damage or corrosion
Measure resistance of the glow plug; compare to specifications
Check for voltage and ground at the glow plug connector with heater commanded on
If wiring and glow plug are good, test or replace the AHCM
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 whether the glow plug, wiring, or control module needs replacement.