U0637

Lost Communication With Hybrid/EV Battery Pack Coolant Control Valve B

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$56–167 (est.)

Symptoms

Check Engine light comes on
The car goes into emergency mode
Reduced engine power
Battery charging problems
Hybrid battery overheating

Causes

Open or short circuit in wiring harness
Battery cooling valve malfunction
Connector problems or contact corrosion
Hybrid ECU malfunction
Software error in the control system

How to Fix

Check the integrity of the wiring harness to the valve
Inspect and clean connector contacts
Check valve resistance and operation
Scan the system for other errors
If necessary, replace the cooling valve
Repair only from an authorized dealer

Related codes

U0636 U0638 U0639