What it means
The control module detects a hydraulic leakage fault associated with electric/auxiliary transmission fluid pump A.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Electric or auxiliary transmission-fluid pump A moves fluid through a hydraulic circuit used to operate the transmission. P0B0C indicates the control module has detected a hydraulic leakage condition associated with that pump, which can reduce pressure even if the motor and its electrical supply work.
Common causes
Most likely first.
- Leak in pump or associated hydraulic circuit
- Pump wear or sealing fault
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and scan for pump A, pressure, and shift-related codes to determine when the leakage condition was detected.
- Check available pump command and hydraulic-pressure data for a pressure drop or inability to build pressure when pump A runs.
- Inspect the pump A housing, connected lines, fittings, and nearby transmission surfaces for fresh fluid wetness or signs of a leak.
- Check transmission-fluid level and condition using the vehicle’s specified procedure, looking for evidence of fluid loss without opening a hot or pressurized system.
- If no external leak is visible, have the pump and associated hydraulic circuit tested for internal leakage or wear using the manufacturer’s procedure.
Common fixes
- Correct a loose or leaking pump A line connection or fitting.
- Replace a damaged hydraulic line or seal at the pump A circuit.
- Repair or replace pump A if its housing, internal clearances, or seals are leaking.
- Restore fluid to the specified level with the correct fluid after the leak is repaired.
Can I keep driving?
Do not continue driving if fluid is visibly leaking, the transmission slips, or shifts become erratic; low hydraulic pressure can quickly damage the transmission. If there are no severe symptoms, limit driving and have the leak checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.