What it means
The auxiliary transmission fluid pump phase U-V-W output reports a circuit high condition. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The auxiliary transmission fluid pump's U, V, and W phase outputs power its three-phase motor. This code sets when the controller detects a high condition on the phase circuit, which can be caused by a short to voltage, a faulty motor, or a driver fault.
Common causes
Most likely first.
- Short to voltage in the pump phase circuit
- Faulty pump motor or driver
- Poor connector connection
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 live transmission data for pump commands and when the phase fault becomes active.
- Inspect the pump connector and U, V, and W phase wiring for chafing, moisture, damaged insulation, pin push-back, or contact with a voltage source.
- While monitoring scan-tool data, carefully move the accessible harness to check whether an intermittent high condition responds to movement.
- Use the vehicle wiring information to test each phase circuit for a short to voltage and inspect connector terminal fit.
- If the phase wiring checks out, test the pump motor and controller driver according to the manufacturer's procedure.
Common fixes
- Clean and reseat a loose or contaminated pump connector.
- Repair phase wiring shorted to voltage or damaged by chafing.
- Replace the auxiliary pump if its motor is faulty.
- Repair or replace the pump controller if the phase driver has failed.
Can I keep driving?
Avoid driving if the transmission slips, shifts harshly or late, or has entered limp mode; pump operation may be compromised and further transmission damage is possible. If it shifts normally, keep driving to a minimum until the circuit is diagnosed.
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.