P0456 - NOT gas cap related
 

Team,

Brand new 40th started throwing a P0456 (evap emissions system - small leak) after 1300 miles. This was not a gas cap issue. Had it cleared, came on again at 1800 miles.

Brought it in today, they checked hoses/clamps/valves/cap, did a smoke test, nothing was found.

Thoughts/recommendations? I am planning on installing intake/CBE/HFCs soon, worth trying to resolve this beforehand? Is a small leak ever associated with the exhaust system... so is it possible the new mods would actually address the issue for me?

not sure, but i'd wait like 3k miles aftr its fixed before you do those mods, because if it happens again it'll be on you even if its the same problem again.

I had the same code come up last week (July 14th) on and had them reset the computer. I then got a SEL on again that fallowing Friday two days later. I then brought the Z in again on Saturday 17th they did a full pressure test of the system and the tech said he could smell a small leak around the gas cap seal it self and nowhere else. In turn they ordered me a new replacement gap and they reset the computer again for me. I then drove the car until Wednesday 21st, I then took it in to get the gas gap replaced.


I have not had another SEL since the Friday 16th,

How are you sure it isn't a gas cap issue?

With this code and others 400 series codes, the gas cap may not be at fault. Often times the charcoal canister will be over pressurized and will split apart inside. This can be caused by, most often times, topping off your gas at the pump rather than stopping when the pump stops. The charcoal canister is built to only allow for so much fume capture before it is overwhelmed and breaks apart.

If you are a topper-offer, mention this to whoever is looking at the car and check into having the canister replaced. If it isn't this, anyone elses guess is as good as mine??

Sorry for the confusion. It certainly could be gas cap issue, I was just trying to say that i'm positive I screwed the gas cap on tightly during fill-ups.

I asked if having the gas cap replaced would fix it and they said they tested tank pressure and everything came out OK. When it happens again i'm thinking i'll have him order a replacement cap just to be safe.

Thanks for the helpful tip. Do you think the canister could realistically break apart after 1,000 miles?

probably not. when the place pressure tested the system, did the take the cap off and put the tester on the filler tube? if so, this won't pick up a gas cap leak. I'd start with replacing the cap. their cheap.

Thats why I was asking about that. It could be the gas cap without it being your fault. Definitely make sure it's checked.

Like it was suggested, wait till this issue gets resolved, and put at least a couple hundred miles on it to make sure it's gone. Then Mod away :driving:

When my dealership pressure tested it, they had a valve accessed in the engine bay to do the pressure test. Then the vapor/smell where detected around the gas cap area..................they didn't do the test with a tube going down into the tank (filler tube).