What it means
The auxiliary transmission fluid pump does not perform as expected when commanded.
At a glance
- Usually lights the check-engine light
How it works
An auxiliary transmission fluid pump circulates fluid when the transmission needs additional hydraulic pressure or lubrication. The transmission controller compares the pump's operation with its command; this code sets when the pump does not deliver the expected performance, which can happen if debris restricts its moving parts or the rotor magnet no longer drives them properly.
Common causes
Most likely first.
- Pump motor seized by sediment
- Cracked rotor magnet decouples drive
- Carbon or debris buildup preventing free movement
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
- Use a scan tool to record freeze-frame data and check transmission fluid temperature, pump command, and related transmission codes to see when performance fell short.
- With the vehicle safely supported and the transmission off, inspect the auxiliary pump and its wiring for damage, contamination, loose connections, or fluid leaks.
- Check fluid condition and level using the manufacturer's procedure, since contaminated or incorrect fluid can contribute to pump drag.
- Command the auxiliary pump with a suitable scan tool and compare its response, current, or speed data with the manufacturer's specification.
- If the electrical supply and control are sound, remove and inspect the pump for sediment, restricted movement, or a cracked rotor magnet.
Common fixes
- Correct the fluid level or service contaminated fluid as specified by the manufacturer.
- Clean debris from the pump or its fluid passage if serviceable.
- Repair damaged pump wiring or a loose connection.
- Replace a seized or internally damaged auxiliary transmission fluid pump.
Can I keep driving?
Avoid towing, hard acceleration, and long trips if shifts are delayed, slipping, or harsh; loss of pump performance can reduce transmission pressure and worsen clutch or gear damage. Stop driving if the transmission slips severely or enters limp mode.
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.