P0442 Code

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Seger

Newbie
Joined
May 23, 2016
Messages
35
Reaction score
3
Location
Indianapolis
I have a 1998 Chevrolet K1500 with a 5.7 Liter Vortec 350. Yesterday my Service Engine Light came on and after scanning for codes it shows a P0442 EVAP System Leak Detected (small leak). Also I noticed after the Check Engine Light came on whenever I am in Drive and idling my truck seems to idle very rough however when I start driving it goes away or if I am in Park and idling it seems to go away. Any thoughts on what this could be?
 

delta_p

OBS Chevrolet, When Silverado Was A Trim
Joined
Jan 8, 2017
Messages
533
Reaction score
388
Location
The Deep South
Does your truck have a fuel tank pressure sensor? My guess is for P0442 small leak, the VCM closes the EVAP purge solenoid and checks the fuel tank for a change in pressure. but probably in normal driving. if the fuel tank pressure remains stable (negative) over the test it passes but if the pressure goes positive it trips the code because a small leak allowed it leak up in pressure.

I would check EVAP vacuum switch because if the diaphragm is busted it won't hold open and will allow a leak. if that works, then i would check the lines for any cracks that goes from the charcoal can over the vacuum switch etc. and check the barbs on the charcoal can itself. It it not any of that, check the EVAP purge solenoid.

My 1996 5.7l doesn't have a fuel pressure sensor so it doesn't have P0442. When my charcoal can barbs cracked i was able to drive around without any issues until i finally fixed it.
 

delta_p

OBS Chevrolet, When Silverado Was A Trim
Joined
Jan 8, 2017
Messages
533
Reaction score
388
Location
The Deep South

Eskimomann209

I'm Awesome
Joined
Jul 22, 2014
Messages
618
Reaction score
217
Gas cap
Change it and reset
OR Simply remove it and re tighten

And when idling do you have fans or a system?
When battery power gets low due to amp draw they like to stumble
 

Seger

Newbie
Joined
May 23, 2016
Messages
35
Reaction score
3
Location
Indianapolis
I received this P0442 Code after the 3 inch body lift I installed. I am think it is most likely at the Fuel Tank Filler Neck area where I had to extend it with the bs they provided. The Fuel Tank Filler Neck itself is pretty rusty so it could also be that or the vent hose that comes off of it. Does anyone know if they make a one piece Fuel Tank Filler Neck that is 3 inches longer than stock with a 2 inch diameter and if so where I can purchase one?
 

Seger

Newbie
Joined
May 23, 2016
Messages
35
Reaction score
3
Location
Indianapolis
It ended up being the Gas Cap so no need for a replacement fuel tank filler neck. Thanks everybody for your help.
 
Top