P27EB code meaning
Transmission Range Control A Position Sensor/Switch Circuit/Open
Powertrain system Generic code P27xx codes Check engine light
What P27EB means
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.
P27EB at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P27EB
- MIL on after the first trip
- Range selection restricted or delayed
Common causes of P27EB
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Range control position sensor aWiring harnessTCM
What each part of P27EB means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 7 | Area: transmission. |
| EB | The exact fault in that area. |
What to do next
- Note P27EB and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P27EB
What does P27EB mean?
P27EB means "Transmission Range Control A Position Sensor/Switch Circuit/Open". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P27EB?
Drive gently and only to a workshop. With P27EB the car can go into limp mode (reduced power) to protect itself.
Will P27EB fail an emissions test?
Yes, it can. P27EB is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P27EB to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P27EB clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.