B2457
Low Severity (Level 2)Aux Heater Coolant Sensor Circuit Open
B2457 usually means aux Heater Coolant Sensor Circuit Open.
Can you still drive with B2457?
⚠️Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
Typical repair cost: $60 – $400
Severity Level 2 — Low
This code indicates a minor issue that is unlikely to cause immediate driveability problems. You can typically continue driving but should have the vehicle inspected at your earliest convenience.
Common Symptoms
- Cabin heat not working — no response when activated
- Cabin heat working intermittently, then stopping completely
- Infinite resistance in the heater circuit — broken wire or disconnected connector
- Fault may be intermittent — code may clear itself and reappear
- Reduced vehicle functionality related to the heater system
Possible Causes
- Broken wire or connector pin in the heater system harness — common at flex points like door jambs or where wiring moves
- Disconnected or loose electrical connector — may have been bumped during other repairs
- Failed heater control valve — internal open circuit from age, heat cycling, or vibration
- Corrosion completely severing a wire or connector terminal — green crust on copper wiring
- Wiring harness damage from rodent chewing — look for nesting material near the engine or under dash
Common Fixes
- Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($13-137 at shop, free at auto parts store for basic scan)
- Visually inspect the heater system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $72 diagnostic fee at shop)
- Trace the heater system wiring from connector to connector with a multimeter set to continuity/resistance mode — find and repair the break in the circuit ($102-347 labor for diagnosis and repair)
- Check and reseat all connectors in the heater system circuit — disconnect, inspect pins, clean with electrical contact cleaner, apply dielectric grease, and reconnect firmly ($11 DIY or $65 shop minimum)
- If heater control valve has failed internally (open circuit inside), replace it — don't try to repair sealed components ($50-400)
Estimated Repair Cost
These are estimated costs based on generic repair data. Actual costs may vary depending on your vehicle, location, and labor rates.
Frequently Asked Questions
What does B2457 mean?
B2457 stands for "Aux Heater Coolant Sensor Circuit Open". B2457 usually means aux Heater Coolant Sensor Circuit Open.
Can you drive with B2457?
Short-distance driving is usually OK, but have this diagnosed within a week to prevent further damage.
How much does it cost to fix B2457?
Repair costs for B2457 typically range from $60 to $400, depending on your vehicle make, model, and local labor rates. Common fixes include: Scan vehicle with a professional-grade OBD2 scanner to read all stored codes and freeze frame data — note the conditions when the code set ($13-137 at shop, free at auto parts store for basic scan); Visually inspect the heater system wiring harness and connectors — look for chafed wires, melted insulation, green corrosion, loose pins, or rodent damage (often free to check yourself, $72 diagnostic fee at shop); Trace the heater system wiring from connector to connector with a multimeter set to continuity/resistance mode — find and repair the break in the circuit ($102-347 labor for diagnosis and repair).
Will B2457 clear itself?
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