B1949 – Climate Control Water Temperature Sensor Circuit Short To Ground

The ODBII code B1949 indicates a malfunction in the climate control system, specifically that the water temperature sensor circuit is shorted to ground, which can affect the system’s ability to regulate temperature properly.

The severity of ODBII code B1949 is moderate.

Common Causes For: B1948 Climate Control Water Temperature Sensor Circuit Failure

• Damaged wiring or connectors
• Shorted sensor
• Faulty climate control module
• Corroded terminals
• Grounding issues
• Water intrusion in the connector or wiring
• Incorrectly installed or loose connections

Common misdiagnosis for B1949 Climate Control Water Temperature Sensor Circuit Short To Ground

• Faulty climate control module
• Bad water temperature sensor
• Wiring issues or shorts in the harness
• Corroded connectors
• Faulty engine coolant temperature sensor
• Issues with the HVAC control system
• Incorrect coolant levels or leaks
• Malfunctioning thermostat

Common Troubleshooting Steps

When dealing with OBD-II code B1949, which indicates a “Climate Control Water Temperature Sensor Circuit Short To Ground,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check the Code and Freeze Frame Data: Use an OBD-II scanner to confirm the B1949 code is present.
• Review freeze frame data to understand the conditions under which the code was set.
• Visual Inspection: Inspect the wiring and connectors related to the climate control water temperature sensor.
• Look for signs of damage, corrosion, or loose connections.
• Check for any frayed wires or shorts to ground.
• Test the Sensor: Locate the climate control water temperature sensor.
• Measure the resistance of the sensor using a multimeter. Compare the readings to the manufacturer’s specifications.
• If the sensor is out of specification, it may need to be replaced.
• Check for Short Circuits: With the vehicle off, use a multimeter to check for continuity between the sensor signal wire and ground. A short circuit will show continuity.
• If a short is found, trace the wiring back to locate the source of the short.
• Inspect the Connector: Check the connector for the climate control water temperature sensor for any bent pins or corrosion.
• Clean the connector and ensure it is securely connected.
• Test the Circuit: With the ignition on (engine off), check the voltage at the sensor connector. You should see a reference voltage (usually around 5V).
• If there is no voltage, trace back to the power source and check for issues.
• Check the Ground: Ensure that the ground connection for the sensor is solid and free of corrosion.
• Test the ground wire for continuity to the vehicle’s ground.
• Inspect Related Components: Check other components in the climate control system that may be related to the water temperature sensor.
• Look for any additional codes that may provide more context.
• Clear the Code and Test Drive: After performing repairs, clear the code using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code returns.
• Consult Service Manual: If the issue persists, consult the vehicle’s service manual for specific diagnostic procedures related to the climate control system and the water temperature sensor.1
• Seek Professional Help: If you are unable to resolve the issue, consider seeking help from a professional mechanic or technician who has experience with your specific vehicle make and model. By following these steps, you should be able to identify and address the cause of the B1949 code effectively.