What it means
Brake Booster Motor A Phase U-V-W Current High: the control module has detected this fault condition. The electric brake booster generates the braking assist; a motor or sensor fault can reduce or disable power-assisted braking. Safety-relevant.
At a glance
- Usually lights the ABS or stability-control warning light
- The engine or gearbox may go into limp mode
How it works
Brake booster motor A is an electric motor used to provide power-assisted braking, and its U, V, and W phase circuits carry motor drive current. The control module monitors current in these phases; C0590 sets when motor A phase current is higher than expected, which can point to a binding motor or an electrical short.
Common causes
Most likely first.
- Brake booster motor A overloaded or binding
- Motor phase wiring short or fault
- Motor or drive circuit fault
- Control module fault
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Save freeze-frame data and check related booster motor codes to see whether high current coincided with motor operation or other electrical faults.
- Inspect motor A and its U, V, and W phase wiring and connectors for damage, pinching, corrosion, or signs of overheating.
- Check whether motor A can move as intended and whether the booster mechanism shows signs of binding, following the manufacturer's safety procedure.
- Test the motor A phase wiring for shorts and compare phase circuit and motor checks with the manufacturer's specifications.
- If the motor and wiring pass, use manufacturer diagnostic procedures to assess the motor drive circuit and brake control module.
Common fixes
- Repair damaged or shorted motor A phase wiring and poor connector contacts.
- Correct a binding brake booster motor A mechanism if the manufacturer's procedure permits service.
- Replace motor A if it fails the specified motor checks.
- Repair or replace the motor drive circuit or control module only after the motor and phase wiring are confirmed sound.
Can I keep driving?
A motor A overcurrent fault can cause reduced or lost brake assist and may disable stability functions. Avoid driving if braking assistance is reduced or warnings are present, and arrange prompt repair.
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.