What it means
The driver stage for the second auxiliary transmission fluid pump does not respond to commands within tolerance.
At a glance
- Usually lights the check-engine light
How it works
The driver circuit controls electric auxiliary transmission fluid pump B and monitors feedback about its electrical response. This code sets when the driver stage or its current feedback does not track the module's commands within the expected range, even if the pump motor itself is not mechanically stalled.
Common causes
Most likely first.
- Aged driver shows degraded switching behaviour
- Current feedback loop noisy
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
- Read freeze-frame data and observe pump B command, current feedback, and transmission symptoms on a scan tool to see when the response becomes abnormal.
- Inspect pump B's connector, wiring, and grounds for loose or corroded terminals, fluid intrusion, chafing, or heat damage.
- Check the pump B supply and ground connections under the manufacturer's specified test conditions to rule out a poor feed or return path.
- Compare commanded pump operation with current feedback using the manufacturer's diagnostic procedure, and move the harness gently while monitoring for interruptions.
- If wiring and connections pass, test the driver stage and feedback circuit as specified before deciding whether the control module or pump assembly is at fault.
Common fixes
- Clean and secure a contaminated or loose pump B connector where appropriate.
- Repair damaged wiring, terminals, or grounds in the pump B driver circuit.
- Replace the pump B assembly if its electrical load is outside the manufacturer's specification and the wiring is sound.
- Repair or replace the control module driver stage only after circuit and load tests identify it as the source.
Can I keep driving?
If shifting is normal, limit driving to a short trip for diagnosis and avoid towing or demanding acceleration. Stop driving if the transmission slips, loses drive, or becomes stuck in one gear, since poor pump control can lead to inadequate hydraulic pressure and further damage.
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.