C05CFBrake Master Cylinder Piston Position Sensor B Circuit Range/Performance
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- Plausibility fault on channel B (GM: PTS2) while its signal is electrically in range. GM's integrated controller with pedal simulator runs the same checks on B as on A: more than 38 mm of travel, a step faster than 700 mm/s that disagrees with channel A and the simulator pressure model, or an offset beyond 2.5 mm, all with 100 ms and Type A. In the booster-type units the B offset with released pedal is limited to 0.9 mm (XT4) or +1.1/-1.5 mm (2023/2025 tables). Wards reported that this vacuum-free ZF system for GM full-size trucks reads the driver's braking wish from a pedal sensor, so a bad channel directly affects brake request. C05CC handles channel A, C05D0 the A/B comparison.
- What you may notice
- Malfunction indicator lamp and brake warning
- Pedal feels different, assist may be reduced
- Likely causes
- LikelyOffset of sensor B outside the allowed range
- PossibleLoose contact causing implausible jumps on channel B
- PossibleSensor rod or mounting worn or bent
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.