U0639

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

1. Check the integrity of the wiring harness to the sensor
2. Inspect the sensor connectors for damage or corrosion.
3. Test the resistance of the temperature sensor
4. Check sensor signals using a diagnostic scanner
5. If necessary, replace coolant temperature sensor B
6. Repair only from an authorized dealer

Related codes

Error U0639 by Vehicle Brand