Have a 2002 x-type that I had tuned up last year and I am getting the same codes again P0171,174,300,301,303,305, P1316. I also have the Power brake not having an assist, tough to stop. I also have Cruise not avail. on the dash. After driving a while on freeway the Cruise light goes out. Before I spend another $700+(checking prices on plugs and gaskets, I got hooked) for a tune up again any suggestions. I have turned wrenches for many years but haven't had time to tinker with this, but now it's time. Thanks for any help.

 

Check the vacuum line coming off your booster for the brakes. You should be able to open your hood with the engine running and hear the hiss. A trick you might try is getting a 2' length of heater hose, using it as a stethiscope with one end up to your ear and the other at any vacuum hose and if you move the vacuum hose and hear a hiss you know you have troubles. I'm willing to bet you do!

Here's a thread with the leaks solved.

https://www.jaguarforums.com/forum/x...ication-37354/

 

Forgot about that trick. bit rusty. Did find the PVC hose hay bailed off the intake. It was shoved in the outer nipple being broke off. Took care of the leak. Jag seems to be happy once again. Thanks again for the response.