P27EDTransmission Range Control A Position Sensor/Switch Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P27ED tells that the Hall sensor on mode valve A of GM's internal range selection delivers almost no voltage. In both the 2018 9-speed and the 2020 10-speed RWD tables the limit is a raw value under 0.414 V for 0.100 s within 0.163 s, with at least 9 V on the battery; GM itself blames a grounded or interrupted line. The code is Type A and lights the MIL on the first trip. Because the TCM then cannot confirm whether the valve has left park, the movement check P27EC is suspended while P27ED is active. Look at the sensor connector inside the transmission and the pass-through plug. High is P27EE, the invalid middle band P27EB, and valve B uses P27F1 for the same fault.
- What you may notice
- MIL lit immediately
- Shifts out of park slow or blocked
- Likely causes
- LikelySensor signal shorted to ground in the internal harness
- PossibleSensor supply open, output collapses
- PossibleHall sensor on mode valve A failed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €150 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.