What it means
The second auxiliary transmission fluid pump motor is commanded on but the rotor does not turn.
At a glance
- Usually lights the check-engine light
How it works
Auxiliary transmission fluid pump B uses an electric motor to circulate transmission fluid and provide hydraulic support. The control module commands the motor and monitors its response; this code sets when the motor is commanded on but does not turn, which can result from a jammed impeller or seized bearing.
Common causes
Most likely first.
- Impeller jammed by sediment or debris
- Motor seized by bearing failure
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 check pump B command and available motor-response data to confirm the no-rotation event and the conditions when it occurred.
- Inspect pump B's wiring and connector for damaged insulation, corrosion, loose terminals, or signs of overheating.
- Check the pump's power and ground circuits under load using the manufacturer's procedure to rule out a supply fault before judging the motor.
- If the circuit tests pass, use the specified pump test to determine whether pump B draws current or produces the expected operating response when commanded.
- If the motor still does not turn, inspect the pump and fluid path for debris or a mechanically seized impeller or bearing as directed by the vehicle's service procedure.
Common fixes
- Repair a loose, corroded, or damaged pump B connector or wiring connection.
- Restore a poor power or ground connection if circuit testing identifies one.
- Remove an obstruction from the pump or fluid path if service access and the manufacturer's procedure allow it.
- Replace pump B if its motor or bearing is seized or the impeller cannot turn.
Can I keep driving?
Avoid driving if shifts are delayed, slipping, or missing, and do not continue if the vehicle loses drive. A pump that cannot turn may leave the transmission without needed hydraulic support, and continued use can worsen internal 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.