P27F2 code meaning
Transmission Range Control B Position Sensor/Switch Circuit High
Powertrain system Generic code P27xx codes Check engine light
What P27F2 means
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.
P27F2 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 P27F2
- Warning light and stored transmission fault
- Neutral or drive selection restricted
Common causes of P27F2
- Most likelyValve B sensor line shorted to a voltage source
- PossibleSensor ground interrupted
- Less likelyHall sensor B electronics faulty
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 bWiring harnessTCM
What each part of P27F2 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. |
| F2 | The exact fault in that area. |
What to do next
- Note P27F2 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 P27F2
What does P27F2 mean?
P27F2 means "Transmission Range Control B Position Sensor/Switch Circuit High". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P27F2?
Drive gently and only to a workshop. With P27F2 the car can go into limp mode (reduced power) to protect itself.
Will P27F2 fail an emissions test?
Yes, it can. P27F2 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 P27F2 to fix?
Difficulty: hard. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P27F2 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.