What it means
The clutch B hydraulic pump motor does not produce the expected flow for the commanded speed. Worn pump, leakage, or aged motor characteristic.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The clutch B hydraulic pump motor drives a pump that supplies fluid flow for clutch operation. The transmission control module compares the expected pump response with the commanded motor speed and sets this code when flow appears insufficient, which can point to a worn pump or a motor whose performance has degraded.
Common causes
Most likely first.
- Hydraulic pump worn
- Motor characteristic aged
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 review commanded pump speed, available flow or pressure data, and related clutch B faults to determine when performance falls short.
- Inspect the pump motor connector and wiring for damage, corrosion or loose terminals that could reduce motor output.
- Check the transmission for signs of hydraulic leakage around the clutch B pump and related lines or connections.
- Using the manufacturer's scan-tool procedure, compare commanded pump operation with the measured hydraulic response to confirm whether output is low.
- If electrical supply and connections are sound, test pump output and motor operation against the manufacturer's specification to distinguish pump wear from motor aging.
Common fixes
- Repair a loose or corroded pump motor connection.
- Repair a confirmed leak in the clutch B hydraulic circuit.
- Replace the worn clutch B hydraulic pump if its measured flow is below specification.
- Replace the pump motor if testing confirms degraded motor performance.
Can I keep driving?
Avoid towing, steep climbs and hard acceleration because weak clutch B hydraulic flow can lead to slipping, shuddering or loss of shifts. If the transmission warning appears or limp mode engages, stop driving when safe and arrange diagnosis.
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.