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C0590 — Brake Booster Motor Phase U V W Current High

Generic OBD-II · all makesChassis

The code indicates that the electric current drawn by the brake booster motor's phase U, V, or W circuit is higher than expected.

Symptoms

What causes it — most likely first

1. Failed brake booster motor

The motor inside the booster can develop an internal short or wear that draws excessive current, triggering the high‑current condition.

2. Wiring or connector fault

Corroded, damaged, or loose wiring/connector in the motor circuit can cause abnormal current readings.

3. Low system voltage

A weak battery, poor ground, or voltage drop can cause the motor to draw more current to maintain required torque.

4. Faulty brake pedal switch or signal

If the switch sends an incorrect signal, the control module may command the motor to operate under unsuitable conditions.

5. PCM/control module issue

A malfunction in the module that controls the motor could misinterpret sensor data and raise the current flag, but this is rare.

How it's diagnosed

  1. Inspect the motor wiring harness and connectors for corrosion, damage, or loose pins.
  2. Measure voltage at the motor supply terminals while the brake is applied to verify proper supply.
  3. Test the motor resistance and current draw using a multimeter or scan tool to compare with specifications.
  4. Check the brake pedal switch and its circuit for proper operation and signal integrity.
  5. Perform a functional test of the brake booster motor using a bench power source if available.
  6. If all hardware checks are normal, evaluate the control module for fault codes or abnormal behavior.

Code facts & related codes

SystemChassis
StandardizationSAE generic — identical on every make

Frequently asked

What is the most common cause of code C0590?

The brake booster motor itself failing or drawing excess current is the most frequent cause.

Can a bad battery cause this code?

Yes, insufficient battery voltage can cause the motor to draw higher current, but it is usually accompanied by other voltage‑related symptoms.

Do I need to replace the PCM to clear C0590?

Replacing the PCM is rarely necessary; the issue is usually resolved by repairing the motor, wiring, or power supply.

Is this code related to the ABS system?

C0590 is specific to the electric brake booster motor and is not directly tied to ABS, though both may share electronic control modules.