P2840Shift Fork D Position Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2840 is the overall circuit code for the shift fork D position input. Mercedes-Benz is the one maker that publicly documents it: in the 8G-DCT (transmission 724.1) of its compact models, P284000 marks an electrical fault of the fork D sensor, and the gearbox has a fifth fork E with its own codes from P2863 upward. The other two published dual-clutch strategies skip this code. GM's Corvette software treats fork D as rod 4 on the even shaft and reports its electrical faults as P2842, P2843 or P2844, and Ford's TR9070 summary does the same for rod position sensor 4. With the position of fork D unknown, the module cannot confirm whether its gear is in or out and normally withholds those ratios until the fault is gone.
- What you may notice
- Gears of fork D withheld, gearbox skips them
- Transmission warning lamp
- Reduced driving comfort in emergency mode
- Likely causes
- LikelyElectrical failure of the fork D position sensor
- PossibleDamaged wiring between fork D sensor and the TCM
- RareTransmission control module input or software fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €200 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.