B1250 – Air Temperature Internal Sensor Circuit Failure

The ODBII code B1250 indicates a malfunction in the air temperature internal sensor circuit, which may involve issues such as a faulty sensor, wiring problems, or a poor connection affecting the sensor’s performance.

The severity of ODBII code B1250 is generally considered moderate.

Common Causes For: B1249 Blend Door Failure

• Faulty air temperature sensor
• Damaged wiring or connectors
• Short circuit in the sensor circuit
• Open circuit in the sensor circuit
• Corrosion at the connector
• Poor ground connection
• Malfunctioning engine control module (ECM)

Common misdiagnosis for B1250 Air Temperature Internal Sensor Circuit Failure

• Faulty Engine Coolant Temperature Sensor
• Malfunctioning Ambient Air Temperature Sensor
• Defective Engine Control Module (ECM)
• Wiring issues or shorts in the sensor circuit
• Incorrectly diagnosed HVAC system problems
• Faulty or clogged cabin air filter
• Issues with the vehicle’s climate control system

Common Troubleshooting Steps

When dealing with OBD-II code B1250, which indicates an “Air Temperature Internal Sensor Circuit Failure,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check for Additional Codes: Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are other issues present.
• Inspect the Wiring and Connectors: **Visual Inspection: Look for any damaged, frayed, or corroded wires and connectors associated with the air temperature sensor.
• **Connector Condition: Ensure that the connectors are securely attached and free of corrosion or dirt.
• Test the Air Temperature Sensor: **Resistance Check: Use a multimeter to measure the resistance of the air temperature sensor. Compare the readings to the manufacturer’s specifications.
• **Voltage Check: With the ignition on (engine off), check the voltage at the sensor connector. It should match the expected voltage as per the vehicle’s specifications.
• Check for Short Circuits: Inspect the wiring harness for any signs of short circuits to ground or to other wires. This can cause incorrect readings or sensor failure.
• Inspect the Engine Control Module (ECM): Ensure that the ECM is functioning properly. Sometimes, a faulty ECM can lead to erroneous codes.
• Check for any software updates or recalls related to the ECM.
• Clear the Code and Test Drive: After performing any repairs or adjustments, clear the trouble code using the OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Replace the Sensor (if necessary): If the sensor is found to be faulty after testing, replace it with a new one. Ensure that the replacement part is compatible with your vehicle.
• Recheck the System: After replacing the sensor, clear the codes again and perform another test drive to ensure that the issue is resolved and that the code does not return.
• Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the B1250 code for your specific vehicle make and model. Manufacturers may have specific fixes or recommendations.
• Seek Professional Help: If you are unable to resolve the issue after these steps, consider consulting a professional mechanic or technician who has experience with your vehicle’s make and model. By following these steps, you should be able to diagnose and address the B1250 code effectively. Always refer to the vehicle’s service manual for specific details and specifications related to your vehicle.