Powertrain, generic (extended)

P27EE Transmission Range Control A Position Sensor/Switch Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The opposite of P27ED: the position sensor of mode valve A reads higher than any valid state. GM's TCM tables for the T87A nine-speed of 2018 and the rear-drive ten-speed of 2020 set P27EE when the raw signal exceeds 2.538 V for 0.100 s inside a 0.163 s sample, describing it as a short to voltage on the sensor circuit; the MIL comes on at once (Type A). A sensor that has lost its ground return can also float upward and mimic a short. While the fault is present, GM blocks the plausibility test P27EC and several pressure checks, since the valve position is unknown. Repairs usually involve the internal harness or the sensor; valve B reports the same condition as P27F2, the open band as P27EB.

Likely causes

Sensor signal shorted to a voltage source
Sensor ground open, signal drifts high
Hall sensor output stage faulty

Symptoms

  • MIL on from the first trip
  • Range changes restricted, possible reduced mode

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–2,000
Time1–6 h

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

Parts involved

range control position sensor awiring harnesstcm

Related codes

P27EBP27ECP27EDP27F2

References: gsi.ext.gm.com, gsi.ext.gm.com.