[jasonfichter]

Hey all, I was hoping to receive help with an issue I'm having. The car is currently throwing a P0446 code Evap code. I can clear it and after about 200 miles it comes back.

The dealer has checked the car and smoked the evaporation system and can't see anything wrong with it. The car is tuned with intake, headers and a ported throttle body. The car ran with the tune and no changes for about 2.5k miles before the code started showing. The dealer says it could be a glitch caused by the tune making it show a false code. My tuner says that is highly unlikely but neither the tuner or dealer have a solution for me.

I know I can just shut off the code in the tune but I want to make sure it is actually a glitch and not something wrong with the car before I do that.

What do you guys think?

[jasonfichter]

Any help would be greatly appreciated.

[camaro5]

What can cause the code P0446:

- faulty vent control valve
- blockage at the vent hose, vent filter or vent control valve
- open or short in the vent control valve circuit
- bad charcoal canister
- EVAP system leak
- faulty EVAP system pressure sensor
- stuck open purge valve (solenoid)

[glopez5]

Wondering if you ever got around to fixing this, my 1le is also throwing this code. Car only has 8k miles. I'm about to make an appointment for this weekend to see if I can bring it in.

[jasonfichter]

Originally Posted by glopez5

Wondering if you ever got around to fixing this, my 1le is also throwing this code. Car only has 8k miles. I'm about to make an appointment for this weekend to see if I can bring it in.

My dealer said there is nothing wrong with the car and they blamed on on the tune.

[Arjan]

Hi guys, I just did a muffler delete on my 2019 SS and this code pop't up.
I'm wondering if it has any thing to do with the change.
Have 15K miles on it.
Please let me know if you find any substantial couches on this.

Thanks Adriaan

[gigo980]

This issue is quite common among american made cars with the auto seal gas cap feature. The cel comes on because the small soft little rubber part on the gas cap has become misshaped from the extensive rubbing against the fuel hose. If you’re bothered by the cel then get the following part replaced: part number 84683322. You won’t be needing 90% of it, just the small black upper piece but I can’t seem to find anyone selling them separately.

[ctrlz]

Originally Posted by gigo980

The cel comes on because the small soft little rubber part on the gas cap has become misshaped from the extensive rubbing against the fuel hose.

If this is a rubber seal leaking, sometimes they can be resurrected with a smear of silicone grease. I have done this many times on conventional gas cap o-rings. If there is a tear, the grease is unlikely to help. Don't use petroleum grease or vaseline on rubber! It will distort the gasket.

Don't think this has anything to do with a tune. Anybody saying that has a lot of explaining to do (which I doubt they are capable of).

For those doing muffler work, I suppose it is possible some of the lines for evap got affected. Most of that stuff sits behind the right rear wheel with lines running over the wheel to the gas tank and fuel filler neck.