What does it mean?
B1257 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Air Temperature External Sensor Circuit Short To Ground .
Air Temperature External Sensor Circuit Short To Ground
Severity
Medium
Can I keep driving?
Usually drivable, but get it diagnosed without delay.
First step
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Locate the sensor, almost always at the front of the car behind the grille or in the front bumper. Check the connector first 2. Test the sensor's resistance against ambient temperature, typical reading is around 2,000-3,000 ohms at room temperature, climbing as it gets colder 3. Check wiring continuity back to the climate or body control module 4. Compare live data against actual ambient, if the sensor reads -40°C, the circuit is open 5. If the sensor is fine and wiring is good, the receiving module (BCM or HVAC) is the next suspect
- BBody
- 1Manufacturer-specific
- 2Body
- 57Sequence number
Codes From the Same System
All Fault Codes- B0001Driver Frontal Stage 1 Deployment Control
- B0002Driver Frontal Stage 2 Deployment Control
- B0003Driver Frontal Stage 3 Deployment Control
- B0004Driver Knee Bolster Deployment Control
- B0005Collapsible Steering Column Deployment Control
- B0010Passenger Frontal Stage 1 Deployment Control
- B0011Passenger Frontal Stage 2 Deployment Control
- B0012Passenger Frontal Stage 3 Deployment Control
Related Similar Codes
- B1250Air Temperature Internal Sensor Circuit Failure
- B1251Air Temperature Internal Sensor Circuit Open
- B1252Air Temperature Internal Sensor Circuit Short To Battery
- B1253Air Temperature Internal Sensor Circuit Short To Ground
- B1254Air Temperature External Sensor Circuit Failure
- B1255Air Temperature External Sensor Circuit Open
- B1256Air Temperature External Sensor Circuit Short To Battery
- B1258Solar Radiation Sensor Circuit Failure
This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.