Smog check fail and ac quit !

[George B]

Before you get too far down the parts path you should do some troubleshooting if you are capable. This is where a good scan tool would be a must to do a complete job. Getting a Tech2 would be ideal and in this case be equal in cost to taking it to a dealer to repair it.

There are a few things that could cause the problem on being obviously a large leak through the gas cap or a damaged line. If not that you need to start at the front and work your way back.

This video goes over the EVAP purge solenoid valve troubleshooting. It’s not the same vehicle but the concept is the same. If it fails it never applies vacuum in the first place thus it thinks there is a leak. I have heard of these being cleaned before.

Next is the EVAP vent valve. This one is located under the truck towards the rear of the tank. If it is stuck open the vacuum applied by the purge valve cannot accumulate in the fuel tank so it will see it as a large leak. You can bench test this valve to see if it functions and there are lots of videos out there about that. Here is one for reference.


The last one I will note is the fuel tank pressure sensor. If this gets flaky the computer doesn’t know the correct tank pressure. Here is a video on how they test this. On a suburban you need to lower the tank to reach it.

This is not a complete list of what may be wrong but it is the big three checks with an issue with the canister or lines being right up there too.

A good scan tool is a must if you don’t want to just throw parts at it.

 

[Rocket Man]

Is there such a thing as a complete P0455 “ kit”..., where you can buy all the parts that it could be causing the code?

Sure- buy a new gas cap, purge valve and vent valve if you want to try all 3, or the canister itself. After that if the code doesn’t go away it’s the lines and you don’t need to buy new ones, just blow them out like mentioned.

 

[treehan77]

If yours is as bad as mine was, you’ll find charcoal all the way to the intake. Check that first, it’s easy and free to remove the house from the intake area and check.

 

[treehan77]

Probably not that bad if you can still fill the tank with gas normally though. Make sure the gas cap seal is in good shape too

 

[Steve Waddington]

Well, I had the fuel pump and filter replaced a year and a half ago, and the gas cap around the same time.

I will try to take a look at all the other stuff. Problem is, since my accident last year, I don’t have the flexibility I used to have.( broken femur in 3 places and fractured hip. Two titanium rods and screws holding the left leg together), so getting under the truck might be difficult, but we’ll see.

It’s not the cost if buying the necessary parts that concerns me now... it’s eliminating as many under-the-truck trips as possible! If I could just get all those parts done at once, it would save a lot of pain.

 

[Rocket Man]

Well, I had the fuel pump and filter replaced a year and a half ago, and the gas cap around the same time.

I will try to take a look at all the other stuff. Problem is, since my accident last year, I don’t have the flexibility I used to have.( broken femur in 3 places and fractured hip. Two titanium rods and screws holding the left leg together), so getting under the truck might be difficult, but we’ll see.

It’s not the cost if buying the necessary parts that concerns me now... it’s eliminating as many under-the-truck trips as possible! If I could just get all those parts done at once, it would save a lot of pain.

Then I suggest buying the vapor canister and purge solenoid and replace both of them while you’re under there. The purge valve is on the fuel rail under the hood and can be done after you replace the others or before.

 

[Steve Waddington]

Would you by any chance know those parts numbers for an 03 Tahoe... or tell me where I might find them?
Thanks!

 

[Rocket Man]

Would you by any chance know those parts numbers for an 03 Tahoe... or tell me where I might find them?
Thanks!

Vent valve is ACDelco 2141091, canister is ACDelco 215407.
Rock Auto https://www.rockauto.com/en/catalog/chevrolet,2003,tahoe,5.3l+v8,1412244,exhaust+&+emission

these are not for flex fuel, if you have flex look up the appropriate parts

 

[Steve Waddington]

time to come up with a side hustle

My entire life is a "side hustle" at this point!

 

[Steve Waddington]

Sure- buy a new gas cap, purge valve and vent valve if you want to try all 3, or the canister itself. After that if the code doesn’t go away it’s the lines and you don’t need to buy new ones, just blow them out like mentioned.

And that's exactly how I spent my day today! Ordered all 3 from Amazon...the ACDelco replacement parts.
Pretty easy job actually...except for the stubborn hose clamp tabs on the Vapor Canister Vent Valve (the one under the truck). Still, pretty quick and easy. And just enough clearance under the truck so that I didn't have to jack it up!! Yes!!

So...now I just have to put some miles on it and see if the CEL comes back on. Hopefully not. BTW, in taking off the old parts, I didn't see any debris or charcoal bits coming out of any lines, and no rust underneath anywhere. And I never had any 'slow-fill up' with the gas, so maybe the charcoal canister itself is ok?

Thanks for all the advice and help guys...greatly appreciated!!!