C0590 code meaning
Brake Booster Motor A Phase U-V-W Current High
Chassis system Generic code C05xx codes Check engine light
What C0590 means
C0590 means the current measured in the drive of booster motor A is too high, mostly checked while the bridge is idle and almost nothing should flow. GM uses it in several units, always Type A with MIL: its 2016/2019 hybrid booster trips on leakage current above 20 A for 5 ms, the XT4 module on an idle offset above 36.1 A or a phase current above 200 A, and the 2023/2025 EBCM tables on a shunt offset above 38 A for 0.2 s. In GM's 2019 IBC unit it also flags a bridge driver whose overcurrent detection fails its power-up self-test. Mitsubishi maps C18E1-19 of the Outlander PHEV brake unit to C0590 with MIL after one trip; booster assist, regeneration and automatic braking stop. On the 2011 Saab 9-5 the number was a damper actuator code.
C0590 at a glance
- Check engine lightYes, usually on
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C0590
- Brake assist warning, much higher pedal effort
- Check engine, ABS or brake warning lamps on
- Regenerative braking and automatic brake functions unavailable
Common causes of C0590
- Most likelyLeaking or partly conducting MOSFET in the booster motor bridge
- PossibleShunt or measuring amplifier offset drifted upward
- PossibleWinding short in booster motor A drawing excess current
- Less likelyBridge driver chip failing its overcurrent self-test
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Brake booster motor aBrake system control module
What each part of C0590 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 90 | The exact fault in that area. |
What to do next
- Note C0590 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C0590
What does C0590 mean?
C0590 means "Brake Booster Motor A Phase U-V-W Current High". C0590 means the current measured in the drive of booster motor A is too high, mostly checked while the bridge is idle and almost nothing should flow. It is a generic code, so it means the same on every make.
Is it safe to drive with C0590?
Drive gently and only to a workshop. With C0590 the car can go into limp mode (reduced power) to protect itself.
Will C0590 fail an emissions test?
C0590 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0590 to fix?
Difficulty: workshop only. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will C0590 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.