U063C code meaning
Lost Communication With Coolant Bypass Valve Actuator B
Network system Generic code U06xx codes Check engine light
What U063C means
U063C is the counterpart for the second networked coolant bypass actuator, B. Stellantis lists it for the 3.0-litre Hurricane straight six: bulletin 18-071-26 (2025 Ram 1500) and bulletins 18-082-26 and 18-083-26 (2025 Jeep Wagoneer and Grand Wagoneer) name U063C next to the circuit and performance codes P0E7C to P0E7F of the same valve. In these cases the root cause is powertrain control module software, and the repair is a PCM check and reflash of about 0.2 hours; no hardware has to be replaced. The MIL is lit. Where no such update applies, a lost bus link to actuator B still points to wiring, connector or the actuator. A failed valve can disturb warm-up, cabin heat or coolant temperature control.
U063C at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.2 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U063C
- Malfunction indicator lamp on
- Codes P0E7C to P0E7F for bypass valve B stored at the same time
- Irregular warm-up or weak cabin heat
Common causes of U063C
- Most likelyPowertrain control module software (Stellantis 18-071-26, 18-082-26, 18-083-26)
- PossibleBus, supply or ground wire to actuator B damaged
- PossibleLoose or corroded actuator B connector
- Less likelyActuator B electronics failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Coolant bypass valve actuator bVehicle bus wiring
What each part of U063C means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3C | The exact fault in that area. |
What to do next
- Note U063C and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U063C
What does U063C mean?
U063C means "Lost Communication With Coolant Bypass Valve Actuator B". U063C is the counterpart for the second networked coolant bypass actuator, B. It is a generic code, so it means the same on every make.
Is it safe to drive with U063C?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U063C fail an emissions test?
Yes, it can. U063C is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U063C to fix?
Difficulty: medium. A typical repair takes 0.2 to 2 hours of work. This is a job for a workshop.
Will U063C clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.