P27AB code meaning
Pressure Control Solenoid E Data Incompatible
Powertrain system Generic code P27xx codes Check engine light
What P27AB means
Solenoid E's characterization data failing the TCM's plausibility test produces P27AB. In GM's 2018 table 18OBDG04 the record is written at vehicle assembly according to the valve body part number and must be rewritten by the dealer whenever the valve body is serviced; a missing or partial block, a device class mismatch, a checksum error or falling axis values all count as failures (Type A, one trip). Valve E is clutch 5 (C45678R) on the 2016 eight-speed, clutch C3 (CB38) on the nine-speed, clutch C4 on the ten-speed and the converter clutch on the CVT. The solenoid itself may be perfect; what is wrong is the table the controller uses to drive it, so harsh or flared shifts can appear.
P27AB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 1.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P27AB
- MIL lit
- Flare or bump on shifts using the clutch behind valve E
- On the CVT, irregular torque converter lock-up
Common causes of P27AB
- Most likelyValve body serviced without rewriting the solenoid data
- PossibleIncomplete programming session after TCM replacement
- Less likelySolenoid class in the data does not match the TCM calibration
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Pressure control solenoid eTCM
What each part of P27AB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| AB | The exact fault in that area. |
What to do next
- Note P27AB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P27AB
What does P27AB mean?
P27AB means "Pressure Control Solenoid E Data Incompatible". Solenoid E's characterization data failing the TCM's plausibility test produces P27AB. It is a generic code, so it means the same on every make.
Is it safe to drive with P27AB?
Drive gently and only to a workshop. With P27AB the car can go into limp mode (reduced power) to protect itself.
Will P27AB fail an emissions test?
Yes, it can. P27AB is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P27AB to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 1.5 hours of work. This is a job for a workshop.
Will P27AB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.