Evap System Repair Cost


Asked by Oct 01, 2016 at 07:22 PM about the 2009 Hyundai Sonata

Question type: Maintenance & Repair

To start off I have a 2009 Hyundai Sonata 4
Cylinder 2.4 L, I was driving it a few days ago and
the CEL came on. I ran my scanner on it and came
back with P0456. I went out and bought a gas cap
and drove it to make a couple of trips hoping that it
was the cheapest fix. It's still on unfortunately so I
called the mechanic I usually go to and he said it's
probably the canister and it was going to cost me
about 700 to replace it. He hasn't done the smoke
test which I have read on a few posts about this
subject. I'm hoping it could be something else? Is
the canister and labor really 700?

9 Answers


EVAC Valve. Canister should not cost that much.


I'm having the exact same issue with my '08 Grand Marquis. Different car, I know, but same trouble code (P0456 very small EVAP system leak detected). Here's what I'm doing. I cleared the computer using my scan tool. I ran the gas tank down to empty and refilled it. Now I'm waiting to see if the check engine light returns. The computer will only run the diagnosis test on the EVAP system if the gas tank is between 3/4 and 1/4. Once I run this tank of gas out I'll check to see if the EVAP readiness monitor has set. If it has and the code/check engine light has not returned I won't worry about it. However, if the EVAP readiness monitor has not set (that's the hardest one to set BTW) I'll keep driving the car as per usual and check it a few more times. If the code/check engine light returns I'll have the gas cap tested then, if the cap is ok, I'll have the system smoke tested. That's the ONLY way to find a very small EVAP system leak. Don't allow someone to throw parts and your hard earned money at it!! HTH. -Jim

1 of 1 people found this helpful.

The canister is about $175 on Rock Auto. You need to know if you have Federal or California emissions. HTH. -Jim


Update: I cleared the computer and filled up the gas tank on my Grand Marquis. Ran the tank down to empty and just now refilled the tank. Scanned the computer and all readiness monitors, including the EVAP system monitor, has reset. Trouble code did not return and the check engine light has remained off. So I really don't know what the computer thought it saw to trigger the check engine light and set the trouble code. Perhaps when I got gas one time last month the guy didn't put the gas cap back on tight enough. In NJ there's no self service filling stations. Both last time and just now I put the cap on myself. Maybe that's the difference. HTH. -Jim

1 of 1 people found this helpful.

Great glad you figured it out. Wow, so there is no self service gas stations in NJ?

1 of 1 people found this helpful.

I'll try that and see what happens. Every time I mention it to a mechanic they tell me it's not worth bringing it in and getting the smoke test done and paying the hourly labor costs.

1 of 1 people found this helpful.

No, enginecreator, it's actually illegal to pump your own gas in NJ. -Jim


I would, Hyundai_Guy. Definitely better than tearing into something that can be left alone. I think sometimes "flukes" do happen. I often advise people to clear the computer and just see what happens. A couple years ago my '03 S- 10 Pick Up threw a code for the catalytic converter. Well the converter wasn't that old so I cleared it and (knock on wood, lol) it hasn't returned. Personally I'd rather spend the money for the smoke test and find out what the problem really is then just throw parts at it hoping it fixes the problem. In the long run proper diagnosis and repair is always cheaper! HTH. -Jim


Sorry to hear that Js08016. I looked it up after I saw that earlier and see that it is a law there since 1949. Now that it has been a lifetime for so many living there many want it to stay that way. I know at times it was great to have someone pump my gas but I have been pumping my own gas now so long its hard to imagine it being illegal to do so elsewhere. I have to say great for those who do not want to pump it themselves but sorry to those who can not pump their own. I do wish that their were a few full service stations left to choose from when desired to use one. I read of the long lines or no attendant around when pulling in to get gas, higher cost per gallon too. I personally believe it should be a right to either pay more for someone else pumping fuel for you if desired and a right to saving money if you want to pump your own. When these people go on a trip outside of NJ they will have to use a fuel pump themselves or ask for help because they have never ran a pump before and if your the owner/operator/user of a auto you should be able to decide for yourself IMO.

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