P27F2Transmission Range Control B Position Sensor/Switch Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- With P27F2 the TCM sees the valve B position sensor above its valid range, which GM interprets as a short to voltage on that circuit. The threshold is 2.538 V, which must persist 0.100 s in a 0.163 s sampling period; GM applies it to internal range selection in the 2018 T87A nine-speed and the 2020 rear-drive ten-speed. The 2020 table rates it Type A; in the 2018 edition the MIL entry for P27F2 is blank. With valve B unconfirmed, GM suspends the movement test P27F0. Apart from a real short, a lost sensor ground can push the reading up, so measure the ground before replacing parts. P27EE is the same fault on valve A, P27F1 the low reading and P27EF the illegal mid-band level. Shifting into neutral or drive may be restricted.
- What you may notice
- Warning light and stored transmission fault
- Neutral or drive selection restricted
- Likely causes
- LikelyValve B sensor line shorted to a voltage source
- PossibleSensor ground interrupted
- RareHall sensor B electronics faulty
- 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.