P27A8Pressure Control Solenoid B 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
- With P27A8 the TCM rejects the stored characterization record of pressure control solenoid B. GM's 2016 eight-speed table 16OBDG03 ties B to clutch 2 (CB12345R) and logs the code within one trip when that record is marked as not programmed. From 2017 on (17OBDG04, 18OBDG04, 20OBDG04) the letter stands for the converter clutch valve of the nine-speed, clutch C2 of the ten-speed and the primary pulley of GM's CVT, checked once during controller initialization and rated Type A. A blank or mismatched block nearly always follows a module swap or valve body job where the part-number-based download was skipped. Expect the MIL; lock-up or shift quality may suffer until the data are written.
- What you may notice
- MIL illuminated
- Converter lock-up shudder or no lock-up on the nine-speed
- Uneven upshifts involving the affected clutch
- Likely causes
- LikelyCharacterization download skipped after TCM or valve body replacement
- PossibleData loaded for the wrong valve body part number
- RareTCM non-volatile memory corrupting the stored block
- 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.