What it means
Brake Booster Motor B Position 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
Brake booster motor B helps create power-assisted braking, and its position sensor reports the motor's movement. The brake control module compares that signal with expected motor operation; C058E sets when the reported position is implausible or outside the valid range, even if the circuit is not simply open or stuck high or low.
Common causes
Most likely first.
- Sensor reading drifted
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
Symptoms
- Brake or ABS warning light
- Brake assist may be reduced or unavailable
How to diagnose it
- Save freeze-frame data and compare motor B commanded position with the sensor reading to identify the operating point where they stop agreeing.
- Inspect the motor B position sensor mounting for looseness and check its connector and harness for damage or poor contact.
- Watch the motor B position signal on a scan tool through its operating range and note drift, jumps, or a signal that fails to track movement smoothly.
- Check the sensor circuit and connector terminals for intermittent resistance or signal disturbance using the manufacturer's procedure.
- Test the motor B position sensor against the manufacturer's specifications and investigate the module only if sensor mounting and wiring pass.
Common fixes
- Secure the motor B position sensor if its mounting is loose.
- Repair poor contacts or damaged wiring in the motor B sensor circuit.
- Replace a motor B position sensor that has drifted or fails range testing.
- Repair or replace the brake control module only after confirming the sensor and circuit are sound.
Can I keep driving?
Brake assist may be reduced or unavailable, making the pedal harder to press and lengthening stopping distance. Avoid driving with abnormal braking or a brake warning light; arrange transport for 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.