B2457: Aux Heater Coolant Sensor Open Circuit
The B2457 code indicates that the control module has detected an open circuit in the auxiliary heater coolant temperature sensor circuit. This sensor monitors the coolant temperature in the supplemental heating system, allowing the module to regulate the auxiliary heater operation. An open circuit means the electrical signal between the sensor and the control module has been interrupted, which can be caused by a faulty sensor, broken wiring, or a disconnected terminal.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty or disconnected auxiliary heater coolant temperature sensor
- Open or broken wiring in the sensor circuit
- Corroded, oxidized, or loose pins in the connector
- Excessive resistance due to a poor splice in the harness
- Intermittent circuit failure caused by wiring movement
3. Symptoms You Will Notice
- Auxiliary heater may not operate or function intermittently
- Check Engine Light or service heater light may illuminate
4. Step-by-Step Diagnosis
Scan for additional codes and note freeze frame data
Visually inspect the auxiliary heater coolant sensor connector and wiring for damage, corrosion, or loose connections
Test sensor resistance and compare to manufacturer specifications
Check for continuity and shorts in the wiring between the sensor and control module
Repair or replace any faulty wiring, connectors, or the sensor as needed
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the auxiliary heater may not work, which could affect cabin comfort in cold weather. The issue is moderate and should be repaired soon to restore full heater function.
How much does it cost to fix?▼
Repair costs typically range from $100 to $300, depending on whether the sensor or wiring needs replacement and labor rates in your area.