I’ve had problems with my 2002 e46 318ci with the 2.0 N42 engine idling badly and then cutting out. After some reading up on Bimmerforums.co.uk it sounded like the cam sensor was faulty. The car started smelling of oil around the same time so before taking it to get any fault codes read I had the covers off the engine to see what was going on.

It seemed like the oil filler cap wasn’t sealing properly, and because of that oil was leaking down the engine and covering the exhaust camshaft position sensor. Oil was also burning off on the exhaust manifold. The plug on the sensor was fiddly to get off as one of the clips holding it on is pushed up against the engine block. I ended up pressing both clips down and prising it off with a screwdriver. It would have been easier to have just undone the single hex bolt attaching the sensor to the engine and then unclipped the plug from the sensor.

The sensor plug was gunked up with oil and so was the sensor itself, so I cleaned them both up and put it all back together. It now idles smoothly and doesn’t cut out.

It was a fairly easy job, so if you get your fault codes read and it’s either of the cam sensors you can probably replace them yourself in half an hour.