P0442, most common cause?
CF Monarch
Joined: Apr 2012
Posts: 6,216
Likes: 438
From: Miami, FL.
Super Moderator
Joined: Mar 2011
Posts: 9,175
Likes: 521
the monitor that runs the p0442 diagnostic has conditions that must be met before running the test....the fuel tank level must be within 1/4 to 3/4 full...if outside of that range the monitor will not run.
small leaks require a evap leak testing machine
small leaks require a evap leak testing machine
Administrator
Joined: Apr 2008
Posts: 7,573
Likes: 47
From: Austin, Texas
More often than not folks go and replace the gas cap to no avail, rarely is it the cap itself.
Check the cap o-ring, make sure it's clean and still pliable , if the rubber is cracked or dried out, replace it (use OEM). If your state requires emissions testing take it a shop and have them test the cap for you it takes a whole 2 seconds.
Make sure the cap sealing area on the filler neck is clean and that you turn the cap tight enough that it clicks a couple of times, do not overfill your tank, when the pump cuts off stop filling, over filling with top offs, will quickly ruin your EVAP system with excess fuel.
Check your EVAP system visually , check the lines for cracked or broken lines and hoses. Its crude but it worked for me, I was able to find a split hose on a Dodge minivan by disconnecting the EVAP line and gently blowing into the various lines, a good connection won't allow you to blow any air into it, if you get a line that's running to the gas tank, you will know by the resistance (it will inflate the gas tank a bit and blow back out at you) Any lines that let you blow air into them easily or offer little resistance, should be traced from endpoint to endpoint.
It's possible that you could have a bad vent valve or purge valve as well, but a little troubleshooting will save you the $$ of throwing parts at it only to find it's a split hose connection that you could have simply trimmed back the rubber line for.
Check the cap o-ring, make sure it's clean and still pliable , if the rubber is cracked or dried out, replace it (use OEM). If your state requires emissions testing take it a shop and have them test the cap for you it takes a whole 2 seconds.
Make sure the cap sealing area on the filler neck is clean and that you turn the cap tight enough that it clicks a couple of times, do not overfill your tank, when the pump cuts off stop filling, over filling with top offs, will quickly ruin your EVAP system with excess fuel.
Check your EVAP system visually , check the lines for cracked or broken lines and hoses. Its crude but it worked for me, I was able to find a split hose on a Dodge minivan by disconnecting the EVAP line and gently blowing into the various lines, a good connection won't allow you to blow any air into it, if you get a line that's running to the gas tank, you will know by the resistance (it will inflate the gas tank a bit and blow back out at you) Any lines that let you blow air into them easily or offer little resistance, should be traced from endpoint to endpoint.
It's possible that you could have a bad vent valve or purge valve as well, but a little troubleshooting will save you the $$ of throwing parts at it only to find it's a split hose connection that you could have simply trimmed back the rubber line for.