C066DService/Park Brake Chamber Pressure Sensor
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C066D covers a fault in the transducer reporting the air pressure inside the service/spring brake chambers of an air-braked vehicle. No maker documents the code, but the diagnosis of real systems is published. Bendix's Intellipark electronic parking brake measures the delivery pressure of every channel with its own transducer and logs J1939 faults for signals shorted high or to ground; if a sensor fails, park status for that unit cannot be shown, rollaway mitigation is lost and the driver is told to chock the wheels. A WABCO (now ZF) patent uses such a sensor to decide whether the spring brakes are applied or released. Knorr-Bremse, which also builds the parking brake into its electronic air control unit, places sensors at the control inlet and the outlet of the relay valve so each reading can serve as a cross-check on the other.
- What you may notice
- Parking brake indicator flashes, park status unknown
- Automatic park functions such as rollaway protection unavailable
- Likely causes
- LikelySensor signal or 5 V supply shorted to ground or voltage
- PossiblePressure transducer in the valve module defective
- RareSensor outputs shorted together or connectors swapped
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.