B1850 – Climate Control Temperature Differential Circuit Open

The ODBII code B1850 indicates that there is an open circuit in the climate control temperature differential sensor, which measures the difference in temperature between the air entering and exiting the climate control system.

The severity of ODBII code B1850 is moderate.

Common Causes For: B1849 Climate Control Temperature Differential Circuit Failure

• Open circuit in the temperature differential sensor wiring
• Faulty temperature differential sensor
• Poor electrical connections or corroded connectors
• Malfunctioning climate control module
• Short circuit in the wiring harness
• Software issues in the climate control system
• Grounding issues in the circuit

Common misdiagnosis for B1850 Climate Control Temperature Differential Circuit Open

• Faulty climate control module
• Wiring issues or shorts in the harness
• Bad temperature sensors
• Incorrectly calibrated HVAC system
• Malfunctioning blend door actuator
• Refrigerant level issues
• Faulty HVAC control head
• Software or programming errors in the climate control system

Common Troubleshooting Steps

The OBD-II code B1850 refers to a problem with the climate control temperature differential circuit, indicating that there is an open circuit in the system. Here are some common troubleshooting steps to diagnose and potentially resolve this issue:

• 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 climate control system.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the climate control temperature differential circuit. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to any connectors that may have been disturbed during previous repairs or maintenance.
• Test the Temperature Sensors:
• The climate control system typically uses temperature sensors to monitor the temperature inside and outside the vehicle. Test these sensors for proper operation using a multimeter.
• Compare the readings from the sensors to the expected values as specified in the vehicle’s service manual.
• Check the Climate Control Module:
• The climate control module (or HVAC control module) may be malfunctioning. Check for any signs of damage or failure.
• If possible, perform a reset or reprogramming of the module according to the manufacturer’s specifications.
• Inspect the HVAC System:
• Check the overall operation of the HVAC system. Ensure that the blower motor, actuators, and other components are functioning correctly.
• Look for any blockages in the air intake or ducting that could affect temperature readings.
• Perform a Continuity Test:
• Use a multimeter to perform a continuity test on the wiring associated with the temperature differential circuit. This will help identify any breaks in the circuit.
• Check for Ground Issues:
• Ensure that all ground connections related to the climate control system are secure and free of corrosion. Poor grounding can lead to erratic behavior and fault codes.
• Consult the Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures and specifications related to the climate control system and the B1850 code.
• 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.
• Seek Professional Help:
• If the issue persists after performing these troubleshooting steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific make and model of your vehicle. By following these steps, you should be able to identify and resolve the issue related to the B1850 code.