Well I know I have a large leak according to my CEL... I also know I'm getting about 12 to 14 MPG... which blows. Its had the light on since I got it. Just haven't had time to get it smoked to find the leak.. its a 2000 xj

 

The question is... if I get the leak fixed up, will I notice more mpg?

 

Doubtful, I've had the same code for awile and I get 18 mpg average

 

Alright so last night I left my auxiliary fan on so I needed a jump. I was also low on gas. So I got a jump and filled up and when I'm stopped (at idle) I'm at about 350 rpm.. my CEL hasn't come back for the leak. But it runs great. Just idles low..

 

Don't get your hopes up I dealt with an evap leak that would not the trigger the code when reset for a day or as long as a few weeks and come back on every time. The computer has to run the test under specific conditions before it triggers the light again. The only way to really keep that light off is to find the leak(s) and plug them or replace the hoses.


I found rtv works as a great seal over the connections if you find a leak haha. Or you can just do it right and replace all the hoses. Just look them over you will probably find the ones with cracks or loose connections.

And dont count on it fixing you gas milage either... I had the same situation and it made no difference when I fixed the leaks.