Network, generic

U063C Lost Communication With Coolant Bypass Valve Actuator B

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

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.

Likely causes

Powertrain control module software (Stellantis 18-071-26, 18-082-26, 18-083-26)

Bus, supply or ground wire to actuator B damaged

Loose or corroded actuator B connector

Actuator B electronics failed

Symptoms

Malfunction indicator lamp on
Codes P0E7C to P0E7F for bypass valve B stored at the same time
Irregular warm-up or weak cabin heat

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€30–800

Time0.2–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

coolant bypass valve actuator bvehicle bus wiring

References: static.nhtsa.gov, static.nhtsa.gov, hella.com.