P27A5Electric/Auxiliary Transmission Fluid Pump B Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P27A5 sets when the control line of auxiliary pump B sits at a level that only a connection to a voltage source can explain. In practice the wire touches a powered conductor, or moisture links it to a neighbouring supply pin. No manufacturer documents P27A5 publicly. For pump A, GM's 2025 TCM tables call the equivalent P2799 and judge it by an impedance below 0.5 Ω from signal to a voltage source in 20 of 25 checks, carried out only while the relevant driver is active and supply voltage is between 9 and 15 V; it is a Type B fault. Depending on how the circuit is built, such a short can leave pump B unable to switch off, which links this code to P27A6. Audi's pump B is the V553 on its 0CJ, 0CK and 0CL gearboxes. Repair centres on the harness; the pump itself is seldom at fault.
- What you may notice
- Stop-start switched off
- Pump B may run continuously or not at all
- MIL after two trips on Type B systems
- Likely causes
- LikelyControl wire chafed against a powered conductor
- PossibleMoisture bridging the control pin to a supply pin
- RareFaulty output stage in the controlling module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.