Powertrain, generic (extended)

P27AF Pressure Control Solenoid J Data Incompatible

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

No manufacturer documents P27AF publicly. By its wording it would mean that the TCM considers the stored calibration of a ninth pressure control solenoid, letter J, invalid. GM's published characterization monitor (P27A7 to P27AE, Type A, run at TCM start-up) stops at H, and Ford reports faulty solenoid data on its 10R and 8F transmissions with its own codes P163E and P163F instead of this series. CARB 13 CCR 1968.2 requires transmission output components to be monitored, so a maker with more valves could use J. If it appears, the logic of the GM siblings applies: data missing after a module or valve body change, wrong data set, or a damaged block. A drivable car with MIL and rough shifts is the likely result.

Likely causes

Solenoid data not loaded after TCM or valve body replacement

Data set for another valve body variant

Corrupted calibration block in TCM memory

Symptoms

MIL illuminated
Rough or inconsistent shifts involving the element behind valve J

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€100–400

Time0.5–2 h

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

Parts involved

pressure control solenoid jtcm

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