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Discussion Starter · #1 ·
Hello, I just wanted to share a simple fix for a curious problem I had. 2012 Impala LT with the 3.6L. Picked it up with 67,000 miles. Not long after it started flipping codes. Mainly P0171 and P0174. One is an Oxygen sensor code and the other is the dreaded fuel lean/rich code. The best symptom was a no start after refueling. Had to tap the gas pedal or floor it to enter fuel clear mode to get it restarted again. Well I found the answer in a Malibu forum and thought I could have saved a bunch of time if I would have found it here instead.

The problem is the EVAP purge valve on the engine. It gets stuck open allowing excess fuel vapors pass by. This is what caused the fuel and O2 codes when driving. And it was definitely flooding the engine with fumes as the gas tank was being refilled. Cheap part, one bolt, and a spring clip and this car is good to go.
 

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^ GBPG, you didn't have an o2 code. P0171= bank#1 lean. P0174= bank#2 lean. Both of which usually indicate a vacuum leak(s), but as you found out, can be other causes.
 

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Discussion Starter · #4 ·
Thanks for the correction, you're right they were both lean codes. The purge valve is located near the throttle body. The car did have 02 codes they just weren't reoccurring like the 171 and 174. Should the thread title be changed? I wanted others to easily find the refuel problem also.
 

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Sorry to revive an old thread, but my 2013 Impala with the 3.6 is throwing the P0171 and P0174 codes as well.
My symptoms are as follows:
- Upon cold starts, car will be fine until I pull out of my garage and go to stop at the stop sign right in front of my apartment upon which it will shudder and nearly stall.
- When refueling it doesn't want to start afterwards. Second try always works.
- Once it does start after refuels, the idle can be very rough, but everything is fine once I get moving (even if I stop after driving a block).
- One day at a rest area I turned it off and the car kept running, very roughly, for about 4 seconds. This was with the key completely out of the ignition. I restarted it, did the same thing upon shutting it off. I then let it sit for a few minutes and it wouldn't repeat the issue. (this occurred one time, about a week before all of the other symptoms appeared)


Do these symptoms match the ones you encountered?
Note: I cleaned the MAF sensor yesterday and the car proceeded to do the cold start issue this morning. Have not refueled in the meantime but I'll put my money on the car not wanting to start when I do refuel next.
 

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Those symptoms sure do sound like an Evap issue... These seems to be a fairly common issue on these 2012+ 8th gen Impalas.

Sent from my HP SlateBook 10 x2 PC using Tapatalk
 

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Hmm... well I guess I'll be running to O'reilly's after work and spending the $42 on a new purge valve. I'll update the thread to let everyone know whether or not everything is working properly again.
The worst part is, when the vehicle reached 45k miles in the spring, I took it to a dealership to inspect the evaporative control system like it says to in the owner's manual (as I was unsure how to do this myself), and all they did was check for codes. They might have found this issue before it ever affected my drivability had they bothered to vacuum check the valve. To be fair the vehicle now has 59k, and the issue started 2-3 weeks ago when it was around 56-7k.
 

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Initial reports are success. Filled up with gas after swapping the valve and started right up. I have pictures and can make a post on how to change out the valve later. Thanks for the help
 

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How to replace Vapor Canister Purge Valve

Hi all,
with my symptoms as listed above, turns out the issue was the vapor canister purge valve. It's a relatively cheap part which you can get or order from most auto part stores. I bought a Dorman one Part No: 911-082 from an O'Reilly's because they had one in stock. It was $42. It's extremely simple to install, as long as you can use a ratchet you're in luck!

Tools you need: 10 mm socket and ratchet (1/4 or 3/8 drive will work, 1/2 may not fit)

Steps:
  • Remove the engine cover
  • Locate purge valve
  • Ensure car is off, key is out of ignition
  • Remove electrical clip from valve (there is a tab on the left (passenger/front) side of the clip which you push need to lift a tad and it comes right out.
  • Remove vapor line. Has a quick connect. Simply push down on the top of the white ring and while holding that down pull on the line and it'll pop right off.
  • There's a 10mm head bold holding it in. It's tucked under the electrical and hose connectors.
  • Pull off purge valve
  • Place new purge valve in
  • Tighten 10 mm bolt to 12 ft-lbs (I don't think this is a crucial number to hit, just tighten it comfortably with the socket so the valve doesn't wobble when you try to wriggle it)
  • Reattach hose (just slide it on until it clicks)
  • Reattach electrical clip
  • Replace engine cover

The whole process should only take 10 minutes or so. Assorted images are attached. Hopefully this helps someone else with this issue. :)
 

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^ Josh, was your vapor line stuck on the nipple pretty good? I pushed down and held the white ring and the hose didn't want to release/disconnect.
 

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Hi Sheila, it took a good amount of force to pull the vapor line off. Just make sure you're pushing on the bump on the white ring and give it a good tug or two. Otherwise, get another person to help you out. I'd say use some locking pliers for leverage, but you don't want to damage that vapor line or you'll have to replace that too.
Hope it all goes well!
 

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Hi all,
with my symptoms as listed above, turns out the issue was the vapor canister purge valve. It's a relatively cheap part which you can get or order from most auto part stores. I bought a Dorman one Part No: 911-082 from an O'Reilly's because they had one in stock. It was $42. It's extremely simple to install, as long as you can use a ratchet you're in luck!

Tools you need: 10 mm socket and ratchet (1/4 or 3/8 drive will work, 1/2 may not fit)

Steps:
  • Remove the engine cover
  • Locate purge valve
  • Ensure car is off, key is out of ignition
  • Remove electrical clip from valve (there is a tab on the left (passenger/front) side of the clip which you push need to lift a tad and it comes right out.
  • Remove vapor line. Has a quick connect. Simply push down on the top of the white ring and while holding that down pull on the line and it'll pop right off.
  • There's a 10mm head bold holding it in. It's tucked under the electrical and hose connectors.
  • Pull off purge valve
  • Place new purge valve in
  • Tighten 10 mm bolt to 12 ft-lbs (I don't think this is a crucial number to hit, just tighten it comfortably with the socket so the valve doesn't wobble when you try to wriggle it)
  • Reattach hose (just slide it on until it clicks)
  • Reattach electrical clip
  • Replace engine cover

The whole process should only take 10 minutes or so. Assorted images are attached. Hopefully this helps someone else with this issue. :)
You are the greatest! Thanks bud!
 

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I'm glad to help! This seems to be a common issue based on the number of people who have already used this thread. Hopefully it can help a bunch of people out
 

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If you don't mind my asking and if you can remember, did your purge valve make a very loud ticking sound before it went bad? It ticking would be unmistakable and easy to hear in the car especially after a cold start if you were sitting in it waiting a few minutes for it to warm up.
 

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No, it did not. The only ticking I get from the engine bay is that of the injectors. The 3.6 has direct injection and so uses solenoids to open and close the injectors.
If you're positive that it's the purge valve ticking really loudly, then you can always replace it to see if it fixes your issue. They also contain a solenoid which should click, but normally you shouldn't be able to hear it in the vehicle, and I imagine it'd blend in with the injectors when outside the vehicle.
 

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Would anybody happen to know where this part is located on the 2014 model (new body style) 9th gen???? Any help would be greatly appreciated
 

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Hello, I just wanted to share a simple fix for a curious problem I had. 2012 Impala LT with the 3.6L. Picked it up with 67,000 miles. Not long after it started flipping codes. Mainly P0171 and P0174. One is an Oxygen sensor code and the other is the dreaded fuel lean/rich code. The best symptom was a no start after refueling. Had to tap the gas pedal or floor it to enter fuel clear mode to get it restarted again. Well I found the answer in a Malibu forum and thought I could have saved a bunch of time if I would have found it here instead.

The problem is the EVAP purge valve on the engine. It gets stuck open allowing excess fuel vapors pass by. This is what caused the fuel and O2 codes when driving. And it was definitely flooding the engine with fumes as the gas tank was being refilled. Cheap part, one bolt, and a spring clip and this car is good to go.
So, how is this fix done?
 

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Locate the purge valve at the radiator side of the throttle body, unplug elec. conn., disconnect vacuum line by pressing down on top of the white plastic spring clip/clamp while pulling the vac. line off of the valve port and finally, loosen/remove 10mm mounting bolt. Iirc, I paid ~$6 for a new purge valve from Ebay Motors. After fixing my youngest son's '16 Impala LT Limited a few weeks ago, he showed me a letter he had received from Chevy/GM last Sept. stating that if the purge valve fails, they'll fix it for free, lol.
 
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