Repair Instructions
Replace a brake air pressure sensor
One sensor on each air tank. The same part on CN, EU, US and AU trucks.
Part
3521230X9D01
0–1.4 MPa · 24 V ·
25±3 N·m
Tank pressure
11.7
bar
Park, chock the wheels and switch the ignition off. Power down the high-voltage system, then disconnect the 24 V battery negative.
Open the drain valve under the tank and let all the air out. Never unscrew the sensor with air in the tank.
Press the lock tab and pull the 3-pin connector straight off. Keep it clean and dry.
Unscrew the sensor with a wrench on its hex, not on the plastic connector body.
Plug or tape the open port so no dirt gets into the tank.
Clean the connector. Oil or water in it means the air dryer cartridge needs checking.
Screw in the new sensor and torque it to 25±3 N·m on the hex.
Push the connector on until the tab clicks, then tug it once.
Close the drain valve, reconnect the battery negative, switch on and build air. Both circuits rise together and the compressor stops on its own.
Brush soapy water on the sensor thread. No bubbles means no leak. Clear any stored brake faults.