P27B6 code meaning
Internal Control Module Transmission Speed Sensor Performance
Powertrain system Generic code P27xx codes Check engine light
What P27B6 means
P27B6 is the supervision check on the transmission speed signals. GM's 2024 heavy-duty TCM tables work out the output speed that should result from turbine speed and the current gear ratio and set the code, MIL on the first trip, when the raw output speed deviates by 10 or more for at least 10 seconds while output speed is at least 50, the range is not neutral and no shift is under way. Ford's summaries list it as non-MIL; the 2024 issue names tie-up protection (UDS P0701_92) and unintended deceleration (P0701_96) on its eight- and ten-speed automatics. Ford TSB 18-2211 dealt with a lit MIL and P27B6 on 2018 F-150 trucks with 2.7, 3.5 or 5.0 L engines built until 4 May 2018 by reprogramming the PCM. Pure sensor circuit faults carry P0715 or P0720.
P27B6 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.3 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P27B6
- MIL or wrench light
- Harsh or abrupt deceleration events
- Fixed gear or limited shifting
Common causes of P27B6
- Most likelyModule software (Ford TSB 18-2211, PCM reprogramming)
- PossibleTurbine or output speed sensor delivering an implausible signal
- Less likelyDamaged tone wheel or interference on sensor wiring
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
TCMSpeed sensors
What each part of P27B6 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. |
| B6 | The exact fault in that area. |
What to do next
- Note P27B6 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 P27B6
What does P27B6 mean?
P27B6 means "Internal Control Module Transmission Speed Sensor Performance". P27B6 is the supervision check on the transmission speed signals. It is a generic code, so it means the same on every make.
Is it safe to drive with P27B6?
Drive gently and only to a workshop. With P27B6 the car can go into limp mode (reduced power) to protect itself.
Will P27B6 fail an emissions test?
P27B6 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P27B6 to fix?
Difficulty: workshop only. A typical repair takes 0.3 to 4 hours of work. This is a job for a workshop.
Will P27B6 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.