Jeep diagnostic codes
 

Every now and then the check engine light on our 2001 Cherokee lights up. Interesting that it is normally when my wife drives the car. Sometimes the light will go off by itself and stay off for days.

I've purchased a $50 reader. The code is 456 - small evap leak. (It is not the gas cap).

My question. How do the diagnostics work ? Does it take two consecutive faults for the code to be registered - the first stored as pending ? Is the same true to clear the fault - two trips with no error and the light goes out ? Do two 'good' trips remove both the pending and actual fault ?

I need to take the car for inspection later this week. I was going to clear ALL the codes and keep my fingers crossed (and not turn the engine off along the way).

I had that code on my 2001 xj , it ended up to be the hoses at the evaporator canister . all I did was cleaned all the hoses and added some hose clamps to hold the hoses form leaking did not have to clamp them down to tight just snug and then cleared codes no codes after that and that was about 8 months ago .

We had the same situation about a year ago. The mechanic worked on the hoses attached to that canister and - like you - no more codes for months. This time around that is the first area they checked out. No issues found. Apparently the tubing that makes up the system is made up of some rubber and some hard plastic. This time they replaced all the rubber tubing and checked out all the plastic tubing. Actually the next thing we were going to try was replacing the EVAP leak detection pump. The mechanic has a friend (who has no CEL issues) with the same model Jeep as ours and he planned on swapping the parts between the two cars - but he hasn't heard from the guy lately. For some reason I don't quite understand the mechanic insists we would need an OEM part - we can not use the cheaper Dorman part - and that OEM part would run me about $300 USD here. It would cost me about $200 USD to buy one of those smoke detectors - which I may end up doing at some point.