What does it mean?
B1214 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Short in the Rear Evaporator Temperature Sensor Circuit .
Symptoms
- Rear air conditioning cools poorly, or the rear compressor request is inhibited altogether
- Rear temperature value pegged at one extreme and not moving
- Rear blower stuck at a fixed speed or behaving unpredictably in automatic mode
- Musty smell and water on the rear floor if the evaporator drain is blocked
- Climate fault message with the code stored
- Rear system may work briefly from cold and then shut down
Likely causes
- Thermistor shorted internally after contamination or moisture ingress
- Signal wire shorted to ground against the rear HVAC housing, a bracket or a body panel
- Water from a blocked evaporator drain flooding the sensor connector
- Harness pinched under a rear trim panel, seat rail or floor console
- Poor repair splice, or a terminal touching the metal housing after the connector was disturbed
- Wrong sensor fitted with a different resistance range
- Failed input circuit in the rear climate control module holding the line low
How to fix it
- Read the rear evaporator temperature in live data; a fixed implausible value usually indicates a short
- Unplug the sensor and see whether the reading swings to the opposite extreme; if it does, the sensor itself is shorted
- With the sensor unplugged, measure the signal wire to ground: still shorted means a harness fault
- Check the evaporator drain for blockage and look for water inside the housing and connector
- Inspect the harness under the rear trim, seat rails and console for pinch and crush points
- Repair the wiring or replace the sensor, and clear the drain if it is restricted
- Clear the code, run the rear system and confirm the reported temperature moves plausibly as it cools