How to Replace the Eccentric Shaft Sensor on a BMW?
3 Answers
Remove the ignition coil cover of the current vehicle, disconnect the connector, and detach the eccentric shaft sensor seal. After completing the preparatory work, slightly lubricate the sealing surface with engine oil, press in the seal using a special tool, and reconnect the connector.
Last time I replaced the eccentric shaft sensor on my BMW myself. Although it was a bit troublesome, it saved me quite a bit of money. First, disconnect the negative terminal of the battery to ensure safety, then remove the engine cover and use a T-handle wrench to take out the mounting screws. Be careful with the sensor connector—there's a small clip, so don't pull too hard or it might break. Before installing the new sensor, it's best to clean the mounting surface with carburetor cleaner. Don't overtighten the screws; BMW recommends a torque of about 10 Nm. Finally, reconnect the battery and use a diagnostic tool to clear the fault codes. After starting, the idle is much more stable, and the previous acceleration hesitation issue is gone. Remember to wear gloves when working on it yourself—the corners of the engine bay can easily scratch your hands.
As someone who frequently repairs BMWs, I believe the key to replacing the eccentric shaft sensor lies in the details. Prepare a 10mm socket and a torque wrench, and it's safer to perform the operation when the vehicle is cold. The disassembly and assembly steps are actually straightforward: disconnect the battery for five minutes, remove the air filter box for easier access, and press the gray clip when unplugging the connector. When installing the new sensor, pay special attention to checking if the gasket is intact, and the screws must be tightened to the factory-specified torque—over-tightening can cause data drift. After completing the job, drive a few kilometers to allow the system to self-learn, and use an OBD tool to check if the camshaft position data is normal. If fault code 1218 appears, you'll also need to inspect the wiring, as sometimes it's an issue with aging wire harnesses.
