Hello,
I am looking to find out where the evap system integrity monitor is for the 2008 aspen. Does anyone have a diagram or tutorial on how to replace it?

 

I had to do a search on this one. Not used to calling it an "Integrity Monitor". The ESIM (Evaporative System Integrity Monitor) which is more commonly called the EVAP Leak Detect Switch on this forum, is mounted to the charcoal canister under the drivers side along the frame between the front and rear doors. You do not have to replace the canister. You can get the ESIM by itself now. This is common to resolve code P0456 and/or "Gas Cap" light. I had the same issue and just replaced the ESIM. A simple 5 minute job. Problem solved.

Simply crawl under the truck on the drivers side about dead center of front and rear doors. Look to the inside of the frame rail. You will see the charcoal canister and the ESIM is between it and the frame rail. Disconnect the electrical connection from ESIM, pull off the hose, push the tab on the ESIM and twist to unlock and remove.

ESIM - 4861959AA
Seal - 52129436AA

Both parts cost me $35.51 from my local dealer back in 2015

Illustration # 5 & 2 on image below:

 

Excellent this worked perfectly. I did have to take some bolts out of the skid plate first to access it so it was a little longer then 5 mins. Thank you for your help now I have to wait and see if this was the fix.

 

You're welcome. Hopefully it works out for you. Keep us posted. I didn't have to remove the skid plate. Guess that's the advantage of having small hands.

 

It definitely worked. Check engine cleared and working great. Thanks again, Mechanic wanted to charge me $320.00 for the parts and labor. Cost $36.00 and about 20-30 mins.