The P0766 code in your 2023 Buick Enclave indicates shift solenoid D is not performing correctly or is stuck in the off position. The Enclave's 9-speed automatic transmission requires proper solenoid operation for smooth, efficient gear changes.
Enclave 9-Speed Transmission
The 2023 Enclave uses GM's 9T65 9-speed automatic, shared across multiple GM crossovers. Shift solenoid D controls hydraulic pressure to specific clutch packs. When stuck off, that clutch engagement is prevented.
Why Solenoid D Gets Stuck Off
- Open circuit in solenoid D wiring
- Solenoid mechanically stuck open
- Valve body passage blockage
- Electrical connector corrosion
- TCM not commanding solenoid
- Internal solenoid coil failure
Symptoms of P0766
- Missing certain gears
- Delayed or harsh engagement
- Check engine light on
- Transmission warning messages
- Degraded fuel economy
- Possible limp mode
GM 9-Speed Reliability
The 9T65 transmission has proven reliable in GM's crossover lineup. Shift solenoid codes are uncommon with proper maintenance. GM recommends using Dexron HP fluid and following prescribed service intervals.