P27ACPressure Control Solenoid F Data Incompatible
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P27AC reports invalid calibration data for pressure control solenoid F. On GM's 2016 eight-speed this is the line pressure solenoid, and the TCM logs the fault in one trip once the data are found unprogrammed. Later GM tables assign F to the nine-speed's C4 clutch, the ten-speed's C6 clutch and the CVT's binary pump; the 2025 table 25OBDG03A still carries the check, with the same start-up test and Type A rating. Because line pressure or pump control rides on this valve in some layouts, a bad record can affect every gear, not just one shift. Typical triggers are a replacement controller or valve body installed without the data download; a faulty solenoid coil sets circuit codes instead.
- What you may notice
- MIL on
- Firm or soft shifts throughout when line pressure depends on valve F
- Possible fixed-gear substitute mode
- Likely causes
- LikelyTCM swapped and solenoid F data never loaded
- PossibleRemanufactured valve body with a new ID not entered into the TCM
- RareData block damaged by a voltage drop during programming
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.