C066EService/Park Brake Chamber Pressure Too High
- Generic OBD-II code · Chassis
- How the car detects it
- C066E means the measured chamber pressure is higher than the module allows in the present state. No maker documents the code, so its limit is not public. Too much pressure in the service section raises the push on the brake directly: Bendix calculates about 1,800 lbf on the pushrod when 60 psi reaches a type 30 chamber, and its chamber tests are not to exceed 120 psig. A specific risk is compounding. A ZF patent from the WABCO family explains that adding service brake force on top of applied spring brakes can permanently damage downsized brakes, and uses the axle's service pressure to release the springs before that happens. Haldex's trailer EBS warns separately when reservoir pressure rises above 9.8 bar, pointing to a governor or valve fault upstream.
- What you may notice
- Brake warning or fault message on the dash or trailer lamp
- Harsh braking or overheated wheel ends after parking manoeuvres
- Likely causes
- PossibleGovernor or pressure regulator letting system pressure rise too far
- PossibleAnti-compound function not working, both forces add up
- RarePressure sensor reading too high
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.