P2879 code meaning
Clutch B Performance/Stuck Disengaged
Powertrain system Generic code P28xx codes Check engine light
What P2879 means
P2879 is set when clutch B does not reach the torque it is asked for, or stays open altogether, so a large speed difference remains across it. No manufacturer publishes a test written for P2879. Mitsubishi shows the method on the clutch A sibling P2871 of the 2023 Outlander PHEV: once parallel mode has run for 2 s, the PHEV-ECU counts phases in which input and output differ by at least 75 rpm over 2 s, and the eighth such phase sets the code with MIL. Ford's 2012 DPS6 summary files the matching clutch B motor fault as P07A4, functionally stuck off; there clutch B drives reverse and the even gears. A car with this fault may refuse reverse, skip 2nd, 4th and 6th or flare without pulling. Worn linings, low apply pressure, a failed actuator motor and wiring faults are the usual suspects.
P2879 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.5 to 10 hours
- Clears after repairAfter a drive cycle
Symptoms of P2879
- Reverse or even gears missing
- Engine speed rises without thrust
- MIL and limp mode
Common causes of P2879
- Most likelyWorn or glazed clutch B slipping under load
- PossibleInsufficient apply pressure from valve body, pump or regulator
- PossibleClutch B actuator motor or its drive failed
- Less likelyWiring fault or control unit not commanding the clutch
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Clutch bClutch actuator bValve body
What each part of P2879 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 8 | Area: transmission. |
| 79 | The exact fault in that area. |
What to do next
- Note P2879 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 P2879
What does P2879 mean?
P2879 means "Clutch B Performance/Stuck Disengaged". P2879 is set when clutch B does not reach the torque it is asked for, or stays open altogether, so a large speed difference remains across it. It is a generic code, so it means the same on every make.
Is it safe to drive with P2879?
Drive gently and only to a workshop. With P2879 the car can go into limp mode (reduced power) to protect itself.
Will P2879 fail an emissions test?
Yes, it can. P2879 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 P2879 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 10 hours of work. This is a job for a workshop.
Will P2879 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.