U063ELost Communication With Exhaust Heat Exchanger Bypass Valve Actuator A
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Exhaust heat recovery passes hot exhaust through a coolant heat exchanger after a cold start, so the engine and cabin warm up sooner; a flap later diverts the gas around it. When that flap's actuator is a LIN slave, losing it gives U063E. GM documents the check in its hybrid tables 16OBDG02 through 19OBDG02, run by the second hybrid powertrain control processor: with the controller on, Run/Crank active, LIN enabled for at least 2 s and battery voltage at least 10.2 V, 80 missed replies at 40 ms intervals (3.2 s) fail it as Type B, MIL after two trips. A stuck flap can slow warm-up or keep heating the coolant when it should not. Circuit and position faults of the flap are P237C to P237F and P2C22 to P2C25; actuator B is U066C.
- What you may notice
- MIL after two drive cycles
- Slower engine and cabin warm-up in cold weather
- Engine runs longer on hybrids to reach operating temperature
- Likely causes
- LikelyActuator electronics damaged by heat near the exhaust
- PossibleLIN or supply wiring under the vehicle damaged or corroded
- PossibleWater ingress or corrosion in the actuator connector
- RareWeak 12 V supply interrupting LIN communication
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.