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B0300: HVAC Evaporator Temperature Sensor Circuit
Standardized SAE J2012 code · B03xx codes
What does B0300 mean?
The HVAC controller reports a fault in the evaporator temperature sensor circuit, used to prevent evaporator icing.
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 Evaporator sensor failure
- Medium Faulty sensor connector
Likelihood is a general estimate across vehicles; your make and model may differ.
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