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Discussion Starter #1
Hello all. I have a 2015 Impala LT V6. I have about 45K miles on the car. About a month ago the check engine light came on and a scan revealed code P0442, small evap system leak.


I tightened the gas cap, reset the light, and soon it came back.


I replaced the gas cap, reset the light, and soon it came back.


I'm about to replace the purge valve and solenoid. I hope that fixes it.


If the light comes back on my last option to fix it myself is to replace the vapor canister. Where is the vapor canister and is there a separate solenoid or anything else I need to change? Is it part number 84080055? I have tried to look online but cannot find a video or even pictures of where the canister is on the new Impala.


Thanks in advance for any help.
 

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Hello all. I have a 2015 Impala LT V6. I have about 45K miles on the car. About a month ago the check engine light came on and a scan revealed code P0442, small evap system leak.
[snip]
I'm about to replace the purge valve and solenoid. I hope that fixes it.

If the light comes back on my last option to fix it myself is to replace the vapor canister. Where is the vapor canister and is there a separate solenoid or anything else I need to change? Is it part number 84080055? I have tried to look online but cannot find a video or even pictures of where the canister is on the new Impala.
I agree with Bowtie396, take it to the dealer.

That said, out of curiosity, I looked on 3 websites trying to get more info, to see if there are two valves in this system, or only one. My Cruze has two, for example, one at the tank/canister, and one under the hood.

For your Impala, Autozone shows only one "canister purge valve". They have a drawing, but it's not clear in the drawing where the part is located. Grrrr....

Oreilly shows 5 devices; 4 look like the Autozone part, but one looks very different. They have no drawing, and I can't help wonder if maybe they have an Impala Limited part in the mix, despite me having selected the non-Limited version :)

NAPA shows two parts - one is labeled "Canister Purge Solenoid" while the other ls labeled "Canister Purge Valve" , but both pics look the same. This is a good example of how the terminology gets munged making things confusing. I'm pretty sure the solenoid is an integral part of the valve which helps explain the two different labels.

Anyway, after having checked 3 retailers, I'm inclined to think there is only one purge valve in this system, not two.

If I were trying to find it, without spending some money on a manual, I'd inspect under the hood looking for it. Follow the fuel lines - it will likely be close to them. After that, remove the rear wheel by the fuel filler neck, and trace back from there looking for the canister. (Don't get under the car without a jackstand and wheel chocks.)

But, as already stated, let the dealer do this one :) While you're there, discuss it with the service writer, ask if there's one or two purge valves in this system, and if they'll print you a drawing, just to have.

HTH.

Doug

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Discussion Starter #4
Thanks all.

I already have the new OEM AC Delco/Bosch purge valve on the way and it is a 10 minute job. It is right at the top of the engine by the firewall. I'll swap it and see if that solves the problem. Between that and the new gas cap I'm out $50.

If the purge valve doesn't fix the issue, it is either the canister filter or honest to goodness leak. I'll call the dealer about changing the canister filter. I am weary of them covering it under warranty because the 2015 warranty states:

Defects and performance for car and light-duty truck emission control systems are covered for the first 2 years or 24,000 miles, whichever comes first. From the first 2 years or 24,000 miles to 3 years or 36,000 miles defects in material or workmanship continue to be covered under the New Vehicle Limited Bumper-to-Bumper Warranty coverage. Specified major components are covered for the first 8 years or 80,000 miles, whichever comes first.

Unless these parts are considered a "specified major component" I'm not covered. I'm sure they will be wear and tear items because they have solenoids.
 

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Discussion Starter #5
I called 2 dealerships. The purge valve and the canister filter are not covered under the emissions warranty. They both stated they would only warranty the ECM or the catalytic converters.
 

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Discussion Starter #7
The purge valve under the hood is part number 12610560, the canister filter under the rear of the car is 84080055. Both parts incorporate the solenoid.

I'll update when I swap them out. Fairly sure at this point it will be the canister filter under the car that is causing the issue but since the purge valve is only about $30 it's getting swapped as well.

The canister filter for California emission equipped cars ends in part number 666.
 

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Don't just throw parts at it. There's no need to spend $150-$200 to change parts that were working just fine when the problem is a $9 sensor.

I just fixed this issue on my GMT800 6.0L pickup. I posted this writeup on troubleshooting the EVAP system on the silveradosierra board.

You don't need a smoke machine to test the EVAP system but you do need to use your brain and your bi-directional scan tool.

The purge valve is damn easy to test. Unplug the electrical connection and the vapor line to the purge valve and check for any vacuum at the purge line connection with the engine running. If there's any vacuum at all with the engine running it's leaking. If it's leaking change it. If the PCM tests the purge valve circuit resistance while it's unplugged it will set a P0443 code from running the engine with the purge valve unplugged.

Does your scan tool allow you to see the tank pressure and command the vent and purge valve positions?

Leave the hood open but turn off the engine and switch the key back to the full ON position with the Engine OFF. If you're hard of hearing get an assistant to listen for you.
-Command the vent valve closed and open (vent is normally open). You should hear a fairly authoritative click from the vent valve solenoid from just behind the fuel tank. No click means you're deaf enough that you can't hear it, the vent valve is knackered, or the wiring is damaged...
NOTE: The ECM tests the wiring to the vent and purge valves for specified resistance through the wiring. If the wiring loop from ground through the vent valve to the ECM shows an open circuit (Infinite resistance) then it usually sets a P0449 code so the wiring is likely OK and the coil is not burned out inside the vent valve.

-Command the Purge valve open and closed. You should hear a click from the engine bay as the valve opens and closes.

Test the fuel tank pressure sensor.
-Take the fuel cap off and look at the tank pressure with the key on. If the tank pressure reads 0.0" Hg the pressure sensor may be OK. If it reads more or less than +/− 0.02" Hg with the fill cap off it's out of spec so it'll have to be changed.
If the tank pressure sensor reads in-spec put the fill cap back on and start the engine for the next test.
-Close the EVAP vent valve and turn up the Purge valve duty cycle... 20% should do the trick. The tank pressure reading should rapidly drop into the negative numbers. If the tank pressure doesn't change at all replace the tank pressure sensor. Even with a fairly nasty leak the pressure will still change. Your fill cap shouldn't make a hissing noise when you pull a vacuum. If it does then the cap O-Ring is knackered or the fill pipe is leaking. If the EVAP system is working properly it should pull enough vacuum that the ECM commands the system back to normal operation with the purge valve set to 20% duty cycle.
--If the tank vacuum bleeds off and there's no hiss from the fill neck area... Climb under the car with a clean section of hose that fits the vent valve and disconnect both hoses from the vent valve... you shouldn't be able to blow through the vent valve even a little bit with it commanded closed.

My pickup had a bad Tank pressure sensor and a bad fuel cap... Folks were saying to replace the more expensive parts of the system that were just fine. I spent $12 on a Stant fuel cap and $15 on a Delphi tank pressure sensor. All done.
 
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I swapped out the purge valve and all is good again. No more light!
Thanks for posting an AAR

Was it a WAG or did you check it?:devil
 

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Discussion Starter #11
Honestly, it took less time to swap the valve than to spend the time evaluating. I swapped it out and drove it a week. Normally, the light would come back on within 48 hours. Now, all is good.

The purge valve I took off would not hold suction. Suspect it was a bad or warped surface inside and not the solenoid itself.

Once I had the engine plastic cover off, the airbox cover and duct came right off and the valve was easy to get to.
 

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Kids these days love acronyms. It is hard to type out stuff I'm guessing...

I did look up WAG and it said wither Wild ass guess or Wives and Girlfriends
AAR brought up After Action Review
 

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How about writing in English for us older folks.
Kids these days love acronyms.
Actually, I think Hatzie's more a boomer than a millenial :)
WAG I got right away, although I usually spell it SWAG :) And I've had the youngsters call me out on that 'cause it means cool to them :)

AAR brought up After Action Review
I was thinking "report", which is pretty much the same thing.

Doug

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They're both military acronyms. They're much older than me and I'm no spring chicken...
AAR is After Action Report. Could be Review as well I guess.
WAG is as you guessed Wild Ass Guess... or SWAG... Seriously Wild Ass Guess.

They fit right in with SNAFU and FUBAR...

I thought the first ones were more common. Dad is a Marine so...
 

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I was in the Navy and never said either of those. Fubar and Snafu are well known however.
 
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My PO442 Code was not cleared until I replaced the FUEL TANK PRESSURE SENSOR.

Which was a bitch and a half!

You'd think there'd be a fireproof safety access above the Tank for EZ Fuel Pump, Fuel Level Sender and Fuel Tank Pressure Sensor R-'in-R's!!!
 

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My PO442 Code was not cleared until I replaced the FUEL TANK PRESSURE SENSOR.

Which was a bitch and a half!

You'd think there'd be a fireproof safety access above the Tank for EZ Fuel Pump, Fuel Level Sender and Fuel Tank Pressure Sensor R-'in-R's!!!
My 1st generation VW Rabbits had access covers under the rear seat. A buddy had an 86 Honda Accord Hatchback with a fuel pump/fuel sender access hole in the floor.

There's a round impression in the trunk floors of the Gen8 Impala but no removable cover.
 
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0442 - Purge Valve

Recently went through this on my '17 Impala. I have to second Hatzie: We backyard mechanics need to learn diagnosis before surgery. Coming from a technical background, my managers hated when other technicians would replace anything and everything that "could" be wrong on the list without testing it first.

The new gas cap wasn't doing it, so I tested the old purge valve with a vacuum gauge. Wasn't holding. Bought a new one to compare. It was holding. Replaced it and no problems since : ) As technologically advanced as new cars have become, the principles remain the same and a vacuum gauge can do the trick sometimes.

As for how the EVAP system works: the Purge Valve usually remains closed until time to purge. The vent valve usually remains open until the system calls for its internal test. This is why a faulty purge valve can affect the way the rest of the car runs since it's essentially a vacuum leak. While the vent valve is one of those annoying parts that only throws a code when it malfunctions.
 

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Pulling a vacuum on the tank side of an EVAP purge valve can point to a bad valve but it's not a super reliable test.
The valve itself is intended to hold vacuum from the manifold side not from the tank side. The tank side should be at atmospheric pressure til the purge valve opens. It will never have vacuum on the tank side with the purge valve closed.
So... a completely working and serviceable purge valve can actually open slightly and leak when you pull a vacuum on the tank side of the valve.

Put a vacuum gauge with a a 4" or 5" dial on the the tank side of the purge valve and look at the readings with the engine running.
It should be stone steady at 0" Hg til you command the purge valve open. If it reads anything with the engine running the valve is leaking.
I have a couple of very old 5" diameter oil filled dial vacuum gauges from the 1940's or 50's that I use for carburetor tuning. The larger diameter vacuum-only gauges have -1" Hg divisions that are roughly 3mm wide so -1/2" Hg is roughly 1.5mm... it's easy to see small changes in vacuum on a big gauge and the oil keeps the needle from bouncing. It's surprising how useful those old tools still are.
 
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