Jaguar X300 Camshaft Position Sensor Repair

P0340 is CAM POSITION SENSOR

Camshaft Position Sensor (CMP)

Car had an intermittent problem where on starting the engine it would crank for 5 seconds without attempting to fire and then burst into life as normal and run perfectly. 

A fellow enthusiast (BobbyRob) at The Jag-Lovers www.jag-lovers.org forum previously had the same problem and suggested the Camshaft Position Sensor as being the problem.  

It was really easy to fit. Set the crankshaft to TDC on cylinder number 1 using the mark on the crankshaft pulley. Look through the little clear plastic lens on top of the CMP cover (see diagrams below) and a round indent will appear in the centre of the window. Now disconnect the electrical connector, loosen the single retaining bolt with an 8mm spanner and pull out the CMP. You will notice that the little indent will rotate anticlockwise when pulling up the CMP. This is because the gear at the end is helical and when refitting the replacement you will need to take this rotation into consideration. Don't turn the engine over, or you'll lose the TDC setting. Refit the replacement CMP, allowing for the clockwise rotation of the CMP when the helical gear is engaging with the mating gear in the engine, and align the little indent through the plastic window. refit the single retaining bolt with the 8mm spanner. Reconnect the electrical connector and the job is done.  For good measure spray some electrical connector cleaner on all the engine connectors I could see.

Here is a CMP extract from the Jaguar X300 workshop manual. It describes why it could take a few seconds for the engine to fire if the CMP is faulty.