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Emissions trouble on 2009 Silverado


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dwebbster
Novice

Oct 26, 2016, 3:29 PM

Post #1 of 8 (349 views)
Emissions trouble on 2009 Silverado Sign In

For several months now I've been fighting some kind of issue with the emissions system on my 2009 Silverado. I'm stuck in a cycle of check engine light coming on, taking it in to be fixed, having it "fixed", then 3-4 weeks later light comes back on. So far it looks like they've changed a faulty vent valve and canister, replaced a purge valve, removed fuel cell and replaced fuel tank pressure sensor, replaced fuel cap and something about reclipping a line from the purge valve to the back of the engine. After all that the light came on once more. I ended up dropping by another mechanic, and they reset the indicator to see if it came back on. Sure enough a few weeks later it's back on again. I would love to take it to a new mechanic, but this one offers free loaner vehicle, and I need that in order to be able to get to work with them having to keep the truck for days at a time. As far as performance I haven't noticed any issues. It drives fine and the fuel mileage seems right where it's always been. I was able to get it inspected and passed all tests during one of the windows where the light was off. I confirmed with Onstar that this is once again an indicator for the emissions system. So would it be a horrible idea at this point to get one of those devices that will reset the indicator light and just deal with that every so often, or do I need to keep fighting this fight until it gets taken care of? I don't want to do something to really mess up the truck, but at the same time this is getting really old really fast. Thank you.
4.8L V8, 75K miles.


kev2
Veteran
kev2 profile image

Oct 26, 2016, 3:42 PM

Post #2 of 8 (344 views)
Re: Emissions trouble on 2009 Silverado Sign In

what is the code you are dealing with?
Are there any other issues - something not working?
Vehicle is STOCK no modifications or add ons.... Any trouble refueling ie pump kicks off often?


dwebbster
Novice

Oct 26, 2016, 4:26 PM

Post #3 of 8 (335 views)
Re: Emissions trouble on 2009 Silverado Sign In

Thanks for looking. I don't have the specific code. I'll see about having it read tomorrow. Fully stock, no changes. Everything works fine as far as I can tell. Refueling is same as always, no issues there.


dwebbster
Novice

Oct 27, 2016, 2:13 PM

Post #4 of 8 (309 views)
Re: Emissions trouble on 2009 Silverado Sign In

According to the good folks at Autozone, the code is P0442, small leak in evaporative emissions(EVAP) system.


kev2
Veteran
kev2 profile image

Oct 27, 2016, 2:26 PM

Post #5 of 8 (306 views)
Re: Emissions trouble on 2009 Silverado Sign In

  
My fast check for that DTC spit out some TSB's - might want to get copies.
Have you done any exhaust work ?
#10-06-04-001, 09-06-04-024, 10-06-04-001B
The engine off natural vacuum (EONV) test is the small leak detection diagnostic for the evaporative emission system. This diagnostic tests the evaporative emission (EVAP) system for a small leak when the key is turned OFF and the correct conditions are met. Heat from the exhaust system is transferred into the fuel tank while the vehicle is operating. When the vehicle is turned OFF and the EVAP system is sealed a change in the fuel tank vapor temperature occurs which results in a corresponding pressure change in the fuel tank vapor space. This change is monitored by the engine control module (ECM) using the fuel tank pressure sensor input. With a leak in the system, the amount of pressure change will be less than that of a sealed system.






































































(This post was edited by kev2 on Oct 28, 2016, 7:25 AM)


dwebbster
Novice

Oct 27, 2016, 3:01 PM

Post #6 of 8 (302 views)
Re: Emissions trouble on 2009 Silverado Sign In

The only things that have been done are what I listed in the first post. I'm pretty clueless about this stuff so I just take it in to be looked at when there's an issue. They've serviced my last three vehicles and this is the first time I've had something like this. Any clue if this is something serious?


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Oct 27, 2016, 3:06 PM

Post #7 of 8 (302 views)
Re: Emissions trouble on 2009 Silverado Sign In

Just wondering, but are they smoke testing this and using a scan tool to do a purge seal test or are they just guessing and replacing stuff? You can use a smoke machine which pressurizes the system, but it won't show a leak if the leak occurs when the system is in vacuum.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Oct 27, 2016, 3:07 PM)


dwebbster
Novice

Oct 27, 2016, 3:14 PM

Post #8 of 8 (298 views)
Re: Emissions trouble on 2009 Silverado Sign In

The last time there it says they did a smoke test, found the cap was leaking and replaced it. When the light came on the first time I actually bought a new gas cap myself to see if that did anything but the light stayed on. Also says they smoke tested it on at least two other visits.


(This post was edited by dwebbster on Oct 27, 2016, 3:16 PM)






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