What does it mean?
B1228 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Short in the Outside Air Temperature Sensor Circuit .
Symptoms
- The outside temperature reads implausibly high or low and never changes with the weather
- The ice warning symbol stays on permanently or never appears
- Automatic climate control makes poor heating and cooling decisions
- AC operation is inconsistent and comfort has to be corrected manually
- The displayed value does not move even after a long drive
Likely causes
- Sensor signal wire chafed against the bumper reinforcement or a bracket and shorted to ground
- Water trapped in the ambient sensor connector bridging the two pins
- Internally shorted thermistor inside the sensor
- Harness pinched during bumper cover, headlamp, or radiator support reassembly
- Signal wire shorted to a nearby 12 V circuit such as a fog lamp or horn feed
- Corrosion inside the sensor body after long exposure to road salt
How to fix it
- Compare the displayed ambient temperature with an actual thermometer reading
- Unplug the ambient sensor; if the code changes to an open circuit fault, the sensor itself is shorted
- Measure the sensor resistance, where a near-zero value confirms an internal short
- With both the sensor and module connectors disconnected, test the signal wire for a short to ground and to battery voltage
- Dry and clean the connector, apply dielectric grease, and repair chafed wiring behind the bumper
- Replace the sensor if it is shorted, clear the code, and verify a realistic reading after a road test