I'm having a problem with the check engine light on my truck coming on repeatedly. I got the P0442 (M) Evap Leak Monitor Meduim Leak Detected A small leak has been detected in the evaportive sysem.

I assumed the likely culprit was the gas cap. Well I replaced it and the cleared the code. Now the light still comes on every once in a while. Usually when the tank gets to about 1/2 full.

Anybody have any ideas what eles could be leaking besides the gas cap? Is there any way to easily elimante this code from the system?

The truck is a 2002 4X4 QC 5.9L

Thanks,
Peter B

 

you always shut it off when you fill it correct, could be a line from the gas tank that has a minor crack in it...check these two things first...

 

Yep, always shut off when filling. Reset the computer today and the filled the tank. We'll see how long it takes to come on a again.

Peter

 

Check the rubber lines running to and from the charcoal box. It will be under the bed, close to where the gas filler tube is. It is a little black box with lines running in and out of it.

 

^^ thank you i couldnt rember what the thing was called

 

+1. Odds are that one of the hoses has a hair-line crack in it. Also, check for proper connection/seal at the hose nippleconnection(s) at the Box.

Good Luck.