changed air filter element now getting P0171 and P0496?

[The Potato]

Just like the title says. I have a 2012 Sonic hatchback LT with a 1.4T and 6 speed. It's got 54K miles on it. I just changed the air filter element (not the cabin filter) with a genuine GM part and suddenly I am getting P0171 as a pending code on my scanguage and have gotten several P0496 with accompanying check engine light, often when I first start up. I have reinstalled the filter element, making sure there are no pinched or dislodged hoses or connections, etc, but it's still doing the same thing. Anybody have any idea why this might have started happening immediately after changing the element? I'm not inclined to go to a dealer unless I have no choice.

Maybe worth noting that over the Winter, it started going into limp home home about once or twice a day, though I can't recall the code. I think it was P2135. It was for throttle position sensor mismatch. I would restart the car a few times and it would go away. As soon as the weather warmed up above constantly freezing, it went away entirely.

TIA for any suggestions.

 

[Stew]

Was the air filter really filthy? The P0171 is a lean code so if it had been leaning out to compensate for a dirty air filter and now there's a fresh one installed it would all of a sudden be reading lean, at least until it re-learns fuel trims.

 

[rdss]

I agree with stew, try disconnecting the battery for an extended period of time and see if that solves the problem.

 

[Blue hedgehog]

P0496 EVAP Flow During A Non-Purge Condition
http://www.obd-codes.com/p0171

 

[The Potato]

I did think about the ECM trying to relearn life without a filthy filter element and yes, it was pretty clogged. I'll pull the battery for a while. That particular code hasn't triggered a CEL/MIL and I figure maybe I was just being paranoid with the endless 'pending' trouble codes the scanguage was showing. I even shut off the alarm feature for pending codes.

The other code (P0496) is the one that's given me a couple CEL/MILs. I have already researched what the code indicates, that's the first thing I do, I am asking if anyone can think of any particular reason why the code may have suddenly started after installing a filter element.

Thanks for the replies!

 

[Italianjoe1]

Did you possibly pinch or remove any other lines going to the intake tract during removal? From the codes it sounds like you have a small air leak after the MAF now, so check anything that plugs in after the airbox, any plastic lines or rubber connections that could have been damaged when you moved stuff around. Probably something very simple.


In regards to the dirty filter and fuel trims, that can't happen like you guys suggested. If the car has learned to remove 10% fuel to compensate for a very dirty filter, which won't happen anyway but hypothetically, when you remove it the car will just learn back to 0%. Trims have to be off by 25% or more normally to set the 0171/0172 trim codes. That's well outside what lack of maintenance can cause.

 

[The Potato]

I did a visual inspection of everything that got moved around back when I removed and reinstalled the filter element, paying attention to what I may have displaced when I pushed the lid up out of the way, but I will check again with special attention towards any small leaks that may have popped up. That's a great suggestion, thanks!

 

[Yosemite Sam]

Also check the flexible hose between the air box and the turbo for cracks.

 

[Luv2xlr8]

Also check the flexible hose between the air box and the turbo for cracks.

Yes, check for this as well. I have the 1.8 but when I was getting the p0171, my hose had cracks all over it.

 

[The Potato]

Thanks again to everyone for the replies and suggestions. Because this is intermittent, I can't say if it's been solved. I went out yesterday and removed the rubber hose between the airbox and the turbo. There weren't any cracks or anything in it, but I did notice the screw on the clamp holding the hose to the airbox was barely tight at all. I had pushed that whole thing up and out of the way to put in the filter element, so maybe it separated the airbox lid and hose a little. The hose was in place, but I imagine some air could creep in if the clamp wasn't good and tight. Is that small of a potential void enough to cause this code to pop up? When I replaced it, I made sure everything was nice and tight and snugged up to where it is supposed to go, so if that's part of the problem, at least that is solved.

One thing I noticed while I was checking stuff under the hood is the loose way the outlet from the PCV (starts at the center of the intake) fits when it comes around the front of the engine and goes into the air inlet for the turbo. It can rotate freely and doesn't seem to me that it would seal all that well, though I can't see how it actually seals, so maybe it does.

 

[Blue hedgehog]

Just out of curiosity, how was the hose that is clamped to the turbo? Mine was loose. I didn't have any codes though. I even started a thread to inform others.
http://www.sonicownersforum.com/for...4t-stock-air-filter-hose-connected-turbo.html

 

[Chevrolet Customer Care]

Hello The Potato,

I am sorry to hear of the concerns you are experiencing. I am glad your fellow forum members have been able to assist you. If anything changes and you'd like to go into the dealership we would be more than happy to set up an appointment or work with your dealership to assist you. If additional assistance is needed please send us a private message with your contact info and VIN.

Thank you,

Andraya R.
GM Customer Care

 

[The Potato]

Just out of curiosity, how was the hose that is clamped to the turbo? Mine was loose.

It seemed to me that the clamps on both ends were looser than they ought to be, so I tightened them up, but the entire problem has not gone away at all.

Since these codes can be related to the Evap canister and solenoid and that stuff, I'd like to check those, but I don't know where to find them. Is there any kind of comprehensive line drawing diagramming what's under the hood of a 1.4T Sonic? I know what most of the stuff is, but some of it is a mystery. Is the evap canister with the solenoid and purge valve in the back near the fuel tank?

Thanks again, everyone.

 

[The Potato]

Since these codes can be related to the Evap canister and solenoid and that stuff, I'd like to check those, but I don't know where to find them. Is there any kind of comprehensive line drawing diagramming an labeling what's under the hood of a 1.4T Sonic? I know what most of the stuff is, but some of it is a mystery. Is the evap canister with the solenoid and purge valve in the back near the fuel tank? Under the hood? Halfway? Which electrical connector(s) under the hood are involved in this process?

Does anyone know where I can find these things in a '12 1.4 hatchback? I am still getting the codes once in a while and when I fill up my gas tank it takes about 10 seconds for it to finish starting.

I gotta get this solved before the end of the month to get an inspection sticker. So any help would be greatly appreciated.

 

[Larrymer]

Have you called the dealer to see if they will look at it? You still have a powertrain warranty and most emissions stuff is covered for a long period of time as well.

 

[The Potato]

I'm sure a dealer can fix it, but I tend to avoid dealers whenever possible. I don't trust them, don't care for being jerked around and can't leave my car somewhere for an indeterminate period of time. I need my car for work.

I figured out where the valve is and ordred a replacement part. Hopefully that fixes it. If not, maybe I'll have to visit the dealer.