Powertrain, generic (extended)

P27AB Pressure Control Solenoid E Data Incompatible

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

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.

Likely causes

Valve body serviced without rewriting the solenoid data

Incomplete programming session after TCM replacement

Solenoid class in the data does not match the TCM calibration

Symptoms

MIL lit
Flare or bump on shifts using the clutch behind valve E
On the CVT, irregular torque converter lock-up

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€100–400

Time0.5–1.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

pressure control solenoid etcm

References: law.cornell.edu, gsi.ext.gm.com, gsi.ext.gm.com.