I need advice on finding the "very small leak" in my 2001 XJ8. Replaced gas cap six years ago and have had no issues. I read elsewhere that the cap is likely NOT the problem and the smoke tests will not detect a small leak I have 30 days to an inspection and resetting the CEL didnt do it. Where shall I begin? Replaced parts of the emission system over the years the major repair about five years ago.

All ideas welcomed.

Thanks

 

Here's a thread for you to check... https://www.jaguarforums.com/forum/s...ch-help-36404/ ...the OP states what probably the issue is for the P0456. Btw, when doing a search for any code for any vehicle put the maker in front, ex. Jaguar P0456, to get more specific details from the manufacturer if available.
If that doesn't cover your issue, this long thread (of which that previous link is in), may be worth your time....https://www.jaguarforums.com/forum/s...-really-45876/

 

Hi Len,

As Highhorse mentions, it is important to always refer to the Jaguar definitions of diagnostic fault codes as they often differ from generic OBDII definitions. Here's the page from the Jaguar 2001 DTC Summaries Guide:



As you can see, for P0456 the guide says to see the possible causes of P0455 but to ignore "fuel cap off" as a possible cause. Most of the other possible causes can be investigated.

I haven't checked the Workshop Manual, but it may contain some pinpoint tests you can conduct to diagnose P0455/P0456. I believe you can download the Workshop Manual from the 'HOW TO quick links' thread on the home page of this X308 forum.

Please keep us informed.

Cheers,

Don