C05D0Brake Master Cylinder Piston Position Sensor A/B Correlation
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- Both travel channels are individually plausible, but they disagree with each other. GM's integrated controller votes two out of three: PTS1, PTS2 and a third travel estimate (BAS); if PTS1 and PTS2 differ by more than 2 mm and one of them also deviates from the third value by over 2 mm, that channel is declared failed after 100 ms. The XT4 booster module allows 2.71 mm, the 23OBDG07 and 25OBDG03B tables 1.5 mm, each for 0.12 s with both channels initialised and otherwise fault-free; all Type A with MIL. Continental describes pedal modules with two travel sensors precisely so a single bad one can be identified. Loose sensor mounting, contamination and connector faults on one channel are typical causes. C05CC/C05CF cover each channel alone.
- What you may notice
- Malfunction indicator lamp and brake warning
- Brake system switches to reduced mode, regeneration may be off
- Likely causes
- LikelyOne sensor channel drifting away from the other
- PossibleMechanical play at the sensor or input rod
- PossibleContact resistance on one channel only
- 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.