U063B

Lost Communication With Coolant Bypass Valve Actuator A

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$17–56 (est.)

Symptoms

Check Engine light comes on
Reduced engine power
Incorrect operation of the cooling system
Possible engine overheating
The car may go into emergency mode

Causes

Open or short circuit in valve circuit
Bypass solenoid valve malfunction
Problems with the wiring harness or connectors
Engine ECU malfunction
Contact corrosion

How to Fix

Check the integrity of the bypass valve circuit
Inspect connectors and wiring harness for damage
Check valve resistance (compare with nominal)
Replace faulty bypass valve if necessary
Reset the error and check if it returns

Related codes

U063A U063C U063D