What it means
Brake Booster Motor A Current Sensor Circuit Range/Performance: the signal is implausible or outside the valid range. 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
The brake booster controller monitors a current-sensor signal for brake booster motor A to assess the motor’s electrical load. C0596 sets when that signal is implausible or outside its valid range, so the controller may not be able to judge motor A operation reliably.
Common causes
Most likely first.
- Sensor reading drifted
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Scan the brake and stability-control modules, save freeze-frame data, and check for related motor, current-sensor, supply-voltage, or communication codes.
- Inspect the brake booster motor A current-sensor connector and wiring for loose terminals, corrosion, chafing, or signs of heat damage.
- Check the sensor mounting and harness routing for looseness or movement that could distort the reading.
- With a capable scan tool, compare the current-sensor reading with motor A command and operation under the manufacturer’s specified test conditions.
- If the signal remains out of range, test the sensor circuit and sensor against the manufacturer’s procedure before condemning the sensor or booster.
Common fixes
- Secure a loose sensor mounting or connector if inspection confirms movement or poor contact.
- Repair damaged wiring or corroded terminals in the motor A current-sensor circuit.
- Replace the current sensor if testing confirms its signal has drifted or is faulty.
- Replace the brake booster motor or controller only if the manufacturer’s tests identify it as the cause.
Can I keep driving?
Brake assist may be reduced, and ABS or stability control may be disabled, so avoid driving until the braking system is checked. Stop safely and arrange recovery if pedal effort or braking response changes.
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.