My 2001 XJ has been throwing code P0456 small evap leak for a while. Changed the gas cap and inspected all the lines. Everything looks good. Shop suggested that I change the leak detection pump (LDP). My Haynes manual doesn't even mention the pump. I found a diagram on the drivers side firewall and was able to locate the thing. Crazy thing is, I can't find anyone who sells them. Napa, Autozone, Checker, all tell me they don't carry that part. There aren't even very many hits for the leak detection pump on this forum. What gives? Anyone know where I can buy one of these things, do I have to resort to going to the dealership...

 

got pic of it

 

yeah post a pic or a link or something! never heard of this Leak Detection Pump

 

is it in this pic

 

did you check the lines under the truck to the canister

 

Yep, that's the one. Wierd that it doesn't show up at all in my Haynes manual. I'm wondering if it is only on a 2001 XJ since there is so little info about it.

Check out Leak Detection Pump Operation and Diagnosis Booklet Pub Number 81-170-00006. Here's a link: http://identifix.com/tsbfiles/056000/054745.pdf

This indicates that the booklet only applies to 2001 Cherokees so maybe 2001 is the only year with a Leak Detection Pump (LDP). Guess I'll learn more from the dealer tomorrow...

 

Got the leak detection pump from the dealer, $100. Easy to install. Dealer said that the 2001 has a different pump, but that 98-2000 also have leak detection pumps in them. Swapping the leak detection pump is a fairly common fix for evap leak code P0456. I'll put out an other update in a month or so if the code stays gone.