WOMS
B code body Medium severity

B1966 A/C Post Heater Sensor Circuit Failure

The OBD2 code B1966 indicates a malfunction in the A/C post heater sensor circuit, which may involve issues with the sensor itself, wiring, or connections affecting the air conditioning system's performance

Definition

The OBD2 code B1966 indicates a malfunction in the A/C post heater sensor circuit, which may involve issues with the sensor itself, wiring, or connections affecting the air conditioning system's performance

Common causes

  • Faulty A/C post heater sensor
  • Damaged wiring or connectors in the sensor circuit
  • Short circuit or open circuit in the wiring
  • Corroded connectors
  • Poor ground connection
  • Malfunctioning A/C control module
  • Software issues in the vehicle's control system

Common misdiagnoses

  • Faulty A/C compressor
  • Refrigerant leak
  • Bad A/C control module
  • Wiring issues or shorts in the harness
  • Faulty temperature sensors
  • Malfunctioning blower motor
  • Incorrect A/C system charge
  • Issues with the HVAC control panel

Troubleshooting steps

  1. 1. 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 affecting the A/C system

  2. 2. Inspect the A/C System

  3. 3. Check the A/C system for any visible signs of damage or leaks

  4. 4. Ensure that the refrigerant levels are adequate. Low refrigerant can affect sensor readings

  5. 5. Examine the A/C Post Heater Sensor

  6. 6. Locate the A/C post heater sensor and inspect it for physical damage, corrosion, or loose connections

  7. 7. Ensure that the wiring harness connected to the sensor is intact and free from fraying or breaks

  8. 8. Test the Sensor

  9. 9. Use a multimeter to test the resistance of the A/C post heater sensor. Compare the readings to the manufacturer's specifications

  10. 10. If the sensor is out of specification, it may need to be replaced

  11. 11. Check the Wiring and Connectors

  12. 12. Inspect the wiring and connectors leading to the A/C post heater sensor for any signs of wear, corrosion, or poor connections

  13. 13. Repair or replace any damaged wiring or connectors

  14. 14. Inspect the A/C Control Module

  15. 15. If the sensor and wiring are in good condition, the issue may lie within the A/C control module. Check for any software updates or known issues with the module

  16. 16. If necessary, perform a reset of the A/C control module

  17. 17. Clear the Codes

    After performing the necessary repairs or replacements, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  18. 18. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the A/C system or the specific code B1966 for your vehicle make and model. Manufacturers may have specific recommendations or known fixes

  19. 19. Seek Professional Help

    If the issue persists after following these steps, it may be best to consult a professional mechanic or technician who has experience with A/C systems and OBD-II diagnostics. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1966 code