P27EBTransmission Range Control A Position Sensor/Switch Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- GM uses this code on automatics with internal electronic range selection (ETRS), where hydraulic mode valves within the valve body set park, reverse, neutral and drive. Mode valve A carries a Hall position sensor. In the 2020 tables for the T87A 10-speed RWD unit, P27EB sets when the raw sensor voltage lands in an invalid band between 1.263 and 1.504 V, debounced at 0.100 s per 0.163 s window, with at least 9 V battery voltage; it is Type A, so the MIL lights on the first trip. Such a level fits neither valve state and usually means a broken signal wire or a failing sensor. Shorts are P27ED and P27EE, implausible movement P27EC; valve B has P27EF. Range changes may be limited until the cause is fixed.
- What you may notice
- MIL on after the first trip
- Range selection restricted or delayed
- Likely causes
- LikelySignal wire of the mode valve A sensor broken or loose
- PossibleHall sensor on mode valve A failing
- PossibleDamaged internal transmission harness or pass-through connector
- 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.