P0B0C
PPowertrainAuxiliary Transmission Fluid Pump Hydraulic Leak
What does this code mean?
Severity : MediumP0B0C indicates hydraulic leakage detected on the auxiliary transmission fluid pump. This electric pump keeps transmission pressure up while the combustion engine is off, for example during start-stop or on a hybrid. The control module sees that the expected pressure is not being reached.
Symptoms
- Check engine or transmission warning light on.
- Start-stop function disabled.
- Harsh or delayed engagement when the engine restarts.
- Possible transmission limp mode.
Possible causes
- Low transmission fluid level.
- Leak at the auxiliary pump, its seals or lines.
- Worn or failing auxiliary pump.
- Faulty internal valve or hydraulic circuit.
- Faulty transmission pressure sensor.
Diagnosis and repair
- Check transmission fluid level and condition.
- Look for leaks around the auxiliary pump and its fittings.
- Read live data: pressure, pump command and pump current.
- Check the pressure sensor, then replace the pump if it is at fault.
- Clear the code and test with several engine stop events.
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Code
P0B0C
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012