C05ED4WD/AWD Clutch B Stuck Engaged
- Generic OBD-II code · Chassis
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Clutch B is still connected although the AWD module has ordered it to open. It is the one code of the clutch B group that a manufacturer documents in detail. Audi stores C05ED00 with symptom code 29725 in the AWD control unit J492 of quattro ultra models (A4, A5, A6, A7, Q5 and their S versions, mainly 2018–2020), and the instrument cluster sporadically reports a four-wheel drive malfunction. The first issue of TSB 2051558 (2018) had the rear differential replaced if the code came back after the test plan; since revision 3 in mid-2020 Audi names wear on the rear differential's shift fork as the cause, removes actuator 2 (V623) and fits a new fork from a repair kit instead of a new differential. Production received an improved fork material.
- What you may notice
- Sporadic four-wheel drive malfunction message
- Rear driveline keeps turning when it should be decoupled, possible noise
- Likely causes
- LikelyWorn shift fork in the rear differential (Audi quattro ultra)
- PossibleClutch B actuator seized in the engaged position
- RareWelded or swollen plates on friction-type clutch B
- Repair
- Hard · Usually a job for a workshop.Typical cost: €300 – €3,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.