B1254 – Air Temperature External Sensor Circuit Failure

The ODBII code B1254 indicates a malfunction in the external air temperature sensor circuit, which may involve issues such as a faulty sensor, wiring problems, or poor connections affecting the sensor’s performance.

The severity of ODBII code B1254 is generally considered moderate.

Common Causes For: B1253 Air Temperature Internal Sensor Circuit Short To Ground

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

Common misdiagnosis for B1254 Air Temperature External Sensor Circuit Failure

• Faulty Engine Coolant Temperature Sensor
• Malfunctioning Ambient Air Temperature Sensor
• Wiring Issues or Short Circuits
• Faulty Engine Control Module (ECM)
• Incorrectly calibrated or installed sensors
• Air Conditioning System Issues
• Faulty Thermostat
• Issues with the HVAC Control Module

Common Troubleshooting Steps

The OBD-II code B1254 indicates a problem with the air temperature external sensor circuit. This code is often associated with issues in the vehicle’s climate control system or air conditioning system. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information about the air temperature sensor and its circuit. This can provide valuable insights into the expected resistance values and wiring diagrams.
• Visual Inspection:
• Inspect the air temperature sensor and its wiring for any visible damage, such as frayed wires, corrosion, or loose connections.
• Check the connector for any signs of dirt, moisture, or corrosion that could affect the connection.
• Test the Air Temperature Sensor:
• Disconnect the sensor and use a multimeter to measure its resistance. Compare the readings to the specifications provided in the vehicle’s service manual.
• If the resistance is outside the specified range, the sensor may be faulty and should be replaced.
• Check the Wiring and Connectors:
• Use a multimeter to check for continuity in the wiring between the sensor and the engine control module (ECM) or body control module (BCM).
• Look for any shorts to ground or open circuits that could be causing the issue.
• Inspect the ECM/BCM:
• If the sensor and wiring are in good condition, the issue may lie within the ECM or BCM. Check for any software updates or known issues related to the control module.
• If possible, use a scan tool to check for any additional trouble codes that may provide more context for the problem.
• Clear the Codes:
• After performing any repairs or replacements, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Professional Diagnosis:
• If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has access to advanced diagnostic tools and equipment. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1254 code.