U0639
Lost Communication With Hybrid/EV Electronics Coolant Temperature Sensor B
U0639 is an OBD-II diagnostic trouble code meaning: Lost Communication With Hybrid/EV Electronics Coolant Temperature Sensor B. Common causes: open or damaged sensor circuit, coolant temperature sensor b malfunction. Estimated repair cost: $50–139.
Symptoms
- Check Engine light comes on
- Reduced performance of the hybrid system
- Activation of emergency operation
- Some hybrid drive features are unavailable
- Error message on the dashboard
Causes
- Open or damaged sensor circuit
- Coolant temperature sensor B malfunction
- Problems with connectors or sensor connection
- Malfunction of the hybrid system control unit
- Short circuit in the sensor circuit
How to Fix
- Check the integrity of the wiring harness to the sensor
- Inspect the sensor connectors for damage or corrosion.
- Test the resistance of the temperature sensor
- Check sensor signals using a diagnostic scanner
- If necessary, replace coolant temperature sensor B
- Repair only from an authorized dealer
Related codes
Error U0639 by Vehicle Brand
FAQ
What does the U0639 code mean?
U0639 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Hybrid/EV Electronics Coolant Temperature Sensor B
What causes a U0639 error code?
The most common causes of U0639 include: Open or damaged sensor circuit; Coolant temperature sensor B malfunction; Problems with connectors or sensor connection; Malfunction of the hybrid system control unit.
How do I fix a U0639 diagnostic trouble code?
To fix U0639: Check the integrity of the wiring harness to the sensor. Inspect the sensor connectors for damage or corrosion.. Test the resistance of the temperature sensor. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U0639?
Yes, but get it checked soon
How much does it cost to fix U0639?
The estimated repair cost for U0639 is $50–139. Actual cost depends on your vehicle, location, and labor rates.
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