[Nor10]

Sorry if this has been answered a bazillion times, but I cant currently search the forums since the feature is disabled.

Anyhow, Yesterday I jumped into my Jeep (2001 Cherokee Limited, 46,400 miles) and got almost out of my development and the check engine light came on. Went to Walmart and picked up an OBD-II scan tool today and found the PO442 Code stored and it was the only code in the system. Looking at this site: [link]www.obd-codes.com[/link] I get the following:

P0442 OBD-II Trouble Code
Technical Description

Evaporative Emission Control System Leak Detected (small leak)
What does that mean?

This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
Symptoms

You likely won't notice any drivability problems.
Causes

A code P0442 most likely means one or more of the following has happened:

* A loose or improperly affixed gas cap
* A non-conforming gas cap (i.e. not factory/original brand)
* A small leak/hole in a fuel vapor hose/tube
* Other small leak in EVAP system
* Faulty vent o-ring seal

Possible Solutions

With a P0442, the most common repair is to:

* Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
* Otherwise, replace the gas cap, or
* Inspect the EVAP system for cuts/holes in tubes/hoses


I cleared the code and reinstalled the gas cap. I can't tell if it was not on right or not, but I am at a 1/4 tank of a recent fill up on Monday and it ran fine the whole time with no problems. I am really hoping it is just the fuel cap, but wondered if anything besides the above could trigger this code. I guess I am looking for previous experience with this. I don't understand how I can go almost a whole tank of gas before the MIL triggers. I thought I read somewhere that the fault codes must be present for 3 consecutive trips before it illuminates the MIL/CEL, but now I can't find the site. Anyone know if thats true? I know I filled it up on the way home from Ocean City. We stopped at a WaWa's for a potty break and then got home and unloaded the Jeep. I then took said Jeep to pick up our dogs. The next day I went to pick up my son at football practice and Jeep was still fine. It wasn't until yesterday, no more than a hundred feet from my driveway the light came on.

Thoughts?

Thanks,
Paul

[bmyohn]

i have the same thing on my '01

the same type of thing is being asked here just and FYI so u can compare
http://www.jeepforum.com/forum/f11/check-engine-light-456220/

[Nor10]

Drove it to work today and I pulled the codes as soon as I got there. It was back in a pending state. I cleared it again and at lunch I went to the gas station and filled it up. Went back to work and pulled the codes again and there was nothing there. Drove it home this evening and pulled the codes again...and again there was nothing there. I am confused...is this thing dumping codes on low tanks of fuel? If so what does that mean? Is the pump that pressurizes the system (LPD??) not able to put enough pressure into the system when the tank is emptier? Could this be an indication that the LPD is going bad? I will definately be watching this and will report back, but if you all have any thoughts I am all ears. I am probably going to pick up a fuel cap from the stealership soon, but I hate wasting money without a clear indication that it will fix the problem.

Thanks,
Paul

[Nor10]

Oh, and shouldn't I hear some sort of pressure release when I remove th egas tank? I dont with this vehicle...

[XJ2Timer]

Mine is now up to a medium leak. Still can't find the problem. Friend at dealer said it usually takes till it becomes a large leak till they can find it doing a smoke test.

I'm thinking about using a propane torch to find the leak. Valve on but flame NOT lit, passing the end of the propane torch along every line while the engine is running. RPM should increase slightly when the vacuum pulls the propane through the leak and into the engine.

I had one hose end at the charcoal canister that had a split in it and thought this was the cause of the leak but after I fixed it and had the codes cleared it came right back.

[Greenz]

This happened to my 01 several times. Then turned to getting PO456 large leak. Replaced the gas cap 8 bucks at Autozone, cleared coded and now no more problems. Same problem and fix with my 02 Grand Caravan. (Same gas Cap part #).

Also drill a 1/4" hole in the gas cap handle and you can reattach the teather.

[bamaric]

I got the 456 code which I actually think is a smaller leak than the 452, but either way I removed the gas cap and screwed it on 5 clicks and 1 1/2 days later I cranked it after work and the check engine light was no longer on. I guess I will wait to see if it comes back on.

[XJ Wagon]

I had the same problem a while back in my 01. At first it was the small leak then I was getting the code for the med. leak. I tried the gas cap first, it did not work. After 4 or 5 trips to my mechanic and a dealer, the problem was finally found to be the gas tank vent valve. It was replaced and I have not had any problems since.

Hope this helps.

[bigdogg232007]

i have the same problem currently and to get it checked cost 2 much just for them to diagnose it again so can some one send a pic showing me where im suppose 2 b lookin or just tell me please

by the way its a 03 jeep grand Cherokee thanks

[Nor10]

I had to have mine smoke tested to find the problem. If it's not the gas cap, I think you'll be better off having someone smoke test the system.

[itasor]

When I first got my XJ it had this code come on. After trying the gas cap replacement and having it come back, it ended up being a hole in a vapor tube. It was replaced under the used car warranty so I don't know any more info than that, sorry.

[SilverXJ]

Originally Posted by Nor10

I had to have mine smoke tested to find the problem. If it's not the gas cap, I think you'll be better off having someone smoke test the system.

x2 With all the hoses and various items thatc am leak it will be a real PIA to try to find it yourself.

[Paul_C]

In PA the inspection station has to remove the gas cap and test it on the emissions machine. Perhaps your mechanic or a local garage can test it for you.

[filluptrk]

On my daughters Accord the evap leak code would come and go for about a year before it got bad enough for the smoke deal to work. These leaks can really be a PITA to find. Phil

[luckylucker]

Great )))))))))))))
WBR,
Alex