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Check Engine Light Codes 455, 442, 496...Need Help!!

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12K views 15 replies 4 participants last post by  cart7881  
J
#1 ·
I have a 04 4x4 Colorado with the 5 cylinder engine. Truck has 181K miles and Check Engine Light came on a few months ago. Truck still runs like it did when I bought it new. No skipping, no rough idling, Etc and still getting good MPG too. Anyways, I had it checked and got these 3 codes...455, 442, and 496. I think they all 3 point back to a evaporative emissions (EVAP) leak. I've changed out the gas cap and the light stayed off 42 miles before it came back on. Anybody have any idea of any one thing that could throw all 3 of these codes or do you think I have several different issues??? Any help or suggestions on where to start would be greatly appreciated.
 
C
#2 ·
P0442: Evaporative Emissions (EVAP) System Small Leak Detected.
P0455: Evaporative Emissions (EVAP) System Large Leak Detected.
P0496: Evaporative Emissions (EVAP) System Flow During Non-Purge.

The first two codes are fairly common and are usually caused by the defective gas cap or a Canister Vent Solenoid. The P0496 doesn't show up as often. It indicates that the system is drawing a vacuum when it shouldn't be. The valve that controls the vacuum is mounted on the engine and it is the Purge Solenoid Valve. It is also the hardest of the components to replace. The Service Manual says to access it through the wheel well. This link doesn't have much helpful info but there is a diagram showing the location on the engine: perge solenoid valve replacement - Chevrolet Colorado & GMC Canyon Forum I'm pretty sure the PN is 12597567. You can get one most anywhere online (RockAuto, Amazon etc.) or Dealer. MSRP (Dealer) price is about $45. Do a "Search" here and over at 355nation.net for more info.
 
J
#3 ·
cart7881 said:
P0442: Evaporative Emissions (EVAP) System Small Leak Detected.
P0455: Evaporative Emissions (EVAP) System Large Leak Detected.
P0496: Evaporative Emissions (EVAP) System Flow During Non-Purge.

The first two codes are fairly common and are usually caused by the defective gas cap or a Canister Vent Solenoid. The P0496 doesn't show up as often. It indicates that the system is drawing a vacuum when it shouldn't be. The valve that controls the vacuum is mounted on the engine and it is the Purge Solenoid Valve. It is also the hardest of the components to replace. The Service Manual says to access it through the wheel well. This link doesn't have much helpful info but there is a diagram showing the location on the engine: perge solenoid valve replacement - Chevrolet Colorado & GMC Canyon Forum I'm pretty sure the PN is 12597567. You can get one most anywhere online (RockAuto, Amazon etc.) or Dealer. MSRP (Dealer) price is about $45. Do a "Search" here and over at 355nation.net for more info.
Click to expand...
Thanks for the info. I just ordered the Canister Vent Solenoid last night and will pick it up after work today. It doesn't look to hard to replace. The Purge Solenoid valve looks like it might be a little harder to get to. I'll clear the codes after replacing the Canister Vent Solenoid and wait to see if I still get the p0496 before moving on to the Purge Solenoid Valve replacement.
 
#5 ·
Yeah I've replaced my purge valve a couple times now, hopefully the other code is a fluke and won't return. Although did you say you cleared all the codes and that one came back?
Did you order the specific Colorado valve or the Hummer one which is way cheaper? Don't know if you stumbled on that info or not.

One thing I have been trying is to not fill up the tank. After the nozzle clicks off, don't add any more gas. I have heard this is what makes the purge valve fail, and I am definitely guilty of doing that.
 
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J
#6 ·
The part I bought is the Canister Vent Valve Solenoid.. The part number is 911-021 and manufactured by Dorman. Cost was like $23.00 at Advance Auto.

But................. I have major problems trying to install it. I loosened the 13mm bolt to free the canister but can't get the unit to drop down to remove the solenoid because of my gooseneck hitch in the bed. They welded angle iron right in front of the canister to bolt the gooseneck to. Only way I see to change the solenoid is to remove the bed which means taking the bed bolts loose, removing the gooseneck hitch, unhooking the tail lights, and removing the gas inlet hose.. I did tap on the old solenoid hoping to maybe free it up but doubt that will help but won't know for sure until the computer resets itself and see if the check engine light comes back on. I imagine I am the only person with a Colorado that pulls a 20ft Gooseneck trailer...
 
#8 ·
There are pictorials online I believe, or youtube vids. on replacing the solenoid. There is a metal tab that is removed to slide the solenoid bracket (and solenoid) off the canister. Before I'd go to these lengths, I think with a little patience you could have the solenoid off the canister with it in place on the truck.
Curious if you have the spare removed or does your hitch somehow keep the spare in the bed? Or wouldn't that matter?
If the bolt is removed you just need to slide the canister in the direction of the bolt just a little to get it (the canister) off the bracket, there is a tab of metal on the opposite side of the canister. Possibly you can pry that tab out if you really can't move the canister even 1/4".
 
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J
#9 ·
Yes.. I had the spare removed and it helps some in seeing the canister but doesn't help in getting the canister out. I'm taking it Saturday to a friends shop and he is going to put it up on a lift and see if he can get to that clip. He has changed them out before and knows exactly where the clip is. I can't move the canister enough to even see the clip. Btw, I tapped on the solenoid and canister best as I could and reset the light. It's been driven 47 miles now and no light yet. I suppose it will probably come back on before 100 miles but keeping my fingers crossed.
 
J
#10 ·
After tapping on the solenoid Wednesday evening...(btw, it is now Friday morning).. I now have 118 miles on it with several cold starts, city driving, and highway driving and haven't had the check engine light come back on YET. It will be inspected in the morning hopefully if it doesn't come back on.
 
J
#11 ·
Got up to 204 miles and on the way to get it inspected and the CEL came back on. Had my friend at the garage to reset the codes and then I drove it 54 miles before trying to get it inspected. I had 2 incompletes when he scanned it. I drove it another day and took it back this morning with 97 miles since it was reset. Same thing, 2 incompletes so they can't inspect it. On a good note, the scan also confirmed "No Pending Codes" which my friend said was a good sign. He said I just have to keep driving it until the computer resets. The 2 incompletes were the EVAP System and the Catalytic System. I have driven it another 100 miles today and will drive it approximately 75 miles tomorrow before having it re-scanned. Anyone else had a problem with "Incompletes" taking a long time to reset??
 
#12 ·
About the only thing I can say is if you don't have the code reset but replace the valve, the light will go out by itself within a few days, so might stand to reason that if you clear the code but don't replace the valve, it may take a few days to get the check engine light again. Or is this flawed reasoning? Anyways, "resistance is futile", replace the valve, LOL. Can you get the bolt out? Again if you remove that, if the side opposite the bolt (other side of the canister) is clear it should be pretty easy to pry the bracket back, then it should come straight down. (Just make sure you don't crack the plastic canister)
 
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J
#14 · (Edited)
Oooohh..forgot to mention that I did NOT change the canister valve. My garage owner friend ran a test on it and it was working properly. He also did a test on the purge valve and it was faulty which is what he kinda expected since he said the 496 code could easily also trip the 455 code because of the way it is plumbed.. So anyways, he ordered a new purge valve and had it delivered 15 minutes later and installed it while I waited then tested again and it was now working as it should. He is pretty sure that the problem is fixed unless there would be a faulty hose or connection somewhere. He knows both valves are working. The problem is getting the codes to reset so it can be inspected. If it resets and the CEL comes back on then he is going to use his smoke machine to check for leaks along the whole EVAP system. If the "Incompletes" reset and the CEL doesn't come back on then he'll be able to inspect it which is what I am hoping for. He said he has seen some vehicles reset in as little as 20 miles and others take as much as several hundred miles..
 
C
#13 ·
I think that your problem is not going to go away without some part changing. Something is preventing these systems from completing the routine self tests and I'll bet the light come back on again soon. I'm also pretty sure that you will end up needing that purge valve (on the engine). It sucks when these things happen in the winter.
 
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