Suggested Hybspec services
Based on the systems affected by this code, we will most likely start with:
B1255
NiskiOpen Circuit in the Outside Air Temperature Sensor Circuit. The climate control controller detected a lack of signal or incorrect voltage in the outside air temperature sensor measurement circuit.
OBD-II (EN): Ambient Air Temperature Sensor Circuit Open
Code B1255 means an open circuit in the outside air temperature sensor – the component responsible for the correct operation of the automatic climate control. The cause may be a damaged sensor, open wiring, or a corroded electrical connector. Diagnosis with a multimeter and OBD scanner is recommended, preferably at an authorized service center or workshop with appropriate equipment.
Symptoms
- Incorrect outside temperature readings on the climate control display or clock - Automatic climate control (AUTO) operates incorrectly or switches to emergency mode - Possible lack of automatic air distribution temperature regulation - Climate control warning light or error message on the dashboard - Missing or incorrect ambient temperature reading in the onboard computer
Possible causes
- Open or short circuit in the outside air temperature sensor signal wire - Damaged NTC sensor (thermistor) – internal short circuit or mechanical damage - Corrosion or oxidized plug/connector of the outside temperature sensor - Damaged climate control controller (HVAC module) or body module (BCM) - Excessive voltage in the circuit caused by a short to power supply positive
Affected systems
Klimatyzacja / HVACModuł nadwozia (BCM)Czujnik temperatury zewnętrznejAutomatyczna regulacja klimatu
Sources and further reading
Does code B1255 require professional diagnostics?
The code alone is not enough. To find the cause, you need to read live data, check freeze frame conditions, and compare with vehicle behavior. Book a diagnostic session.