P0B0BElectric/Auxiliary Transmission Fluid Pump A Motor Supply Voltage 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
- P0B0B reports a supply voltage at the motor of auxiliary pump A that is above the expected range. Subaru documents it on the 2014-15 XV Crosstrek Hybrid (bulletin 16-94-15R), together with P172A: a leaking O-ring at the electric oil pump relief valve can let CVT fluid into the pump motor. The check removes the three U, V and W cables at the oil pump inverter and reads AC voltage across them with the engine held at 1800 rpm in Park; 0.5 V or more means the drive motor and case assembly with the damaged seal must be replaced, less means the cause lies elsewhere. Subaru adds that P0C79, drive motor inverter voltage too high, appears only together with these codes and does not mean the inverter is faulty. P0B09 and P0B0A are the open and low variants.
- What you may notice
- Warning lamp on, hybrid or CVT function restricted
- Possibly P0C79 stored at the same time
- Likely causes
- LikelyCVT fluid entering the pump motor via a leaking relief valve O-ring (Subaru XV Crosstrek Hybrid)
- PossibleSupply circuit shorted to a higher voltage source
- RareOil pump inverter or its voltage sensing faulty
- 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: €150 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.