OK, after the driveshaft exploded under the truck I have a P0440 and found a nice hole in the evap purge line. Fixed that and now I have a P0442 (small leak code). I am thinking evap canister is cracked or the solenoid is stuck somehow. Any way to verify this without replacing parts? Does the dealer Tech II have the intelligence to tell you what part of the system is acting up?

Andrew

 

as far as I know you cannot use a scan tool to figure out what part is leaking. At my shop we have a low pressure smoke machine that we use to fill the evap system with smoke, which is very handy for finding leaks.

 

The tech 2 makes the diag alot easier. You can use it to close both the purge and vent solenoids at the same time. Then you can smoke the entire system. The tech 2 also eliminates comebacks if the tech does the service bay test after the repair, he can tell if the system will pass the self test the next time it runs. But any shop with a smoke machine can test the system if they know how to use it. The p0442 small leak is usually hard to find. In my experiance 90% of the time it ends up being the purge solenoid it gets some type of debre between the pintle and seat. Usually if something is broken or the vent solenoid is messed up it will set a p0440.

 

Read my post in this performance section, I Had that same code 6 months ago for a while. And I couldn't put Gas in the truck for the last week or so.

PN 15138620 is the Tank Vent Solenoid, and may be the problem. Compare the PN for your year truck in the parts dept at the dealer.

 

they have update part number for soldenoid new design. and p0442 is normally gascap

 

Ok just read your post, good info. Gow did you figure out it was your solenoid without plopping down the $70 first to replace it?

 

Looking in the manuals that I have and looking at how the system kind of works. And recgonizing new and different problems like the large pressure in the tank hissing when I take off the gas cap, inability to fill due to the pressure keeping the Spill valve closed. And the tank vents off the pressure with this solonoid, and I thought it may be the problem. I tested it with a 12v DC power supply and it didn't work for ****. Swapped in the new one in 5min and test drove it. It felt much better driving and filled up with gas with no problem.

 

Wow I need to work for GM! I'm a Hyundai tech and our scanner can't do that, it'd be nice since EVAP issues seem to be 90% of our CELs