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Definition only
B0255: HVAC Air Temperature External Sensor Circuit
Standardized SAE J2012 code · B02xx codes
What does B0255 mean?
A fault has been detected in the external (ambient) temperature sensor circuit used by the HVAC and instrument cluster.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Warning light or symbol related to the affected system
- Comfort or safety function impaired
Common causes
- High Ambient sensor failure (often behind front grille)
- Medium Water in connector
Likelihood is a general estimate across vehicles; your make and model may differ.
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B0255 in the community
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