P27A3Electric/Auxiliary Transmission Fluid Pump B Performance/Stuck Off
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P27A3 means auxiliary pump B was commanded but did not deliver: no pressure build-up, too little speed or a motor that does not respond at all. Audi documents the code. Its bulletin 34-17-25, revision 3 from 2017, covers model year 2017 A4, A5, A6 and the 2018 Q5 with the 0CJ, 0CK and 0CL seven-speed twin-clutch boxes and names P27A300, next to P27A6, P276B and U28A0, as possible companions of a rattling gear oil pump V553; a supplier assembly defect was the cause, and the pump is renewed with new bolts. For pump A the matching code is P2797, which GM's 2025 CVT tables set when both pulley pressures stay below 200 kPa during an engine auto-start. Mechanical seizure, low fluid or a weak motor are typical; stop-start goes offline.
- What you may notice
- Rattle from below the car near the gearbox
- Stop-start disabled
- Delayed or harsh engagement after an engine restart
- Likely causes
- LikelyPump B mechanically defective or seized (e.g. assembly fault on Audi V553)
- PossibleFluid level too low, pump draws air
- PossibleWorn pump motor or high resistance in its supply
- 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: €100 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.