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Discussion Starter · #1 ·
I understand that filling up with gas when the car is running is not recommended. I did it once without realizing that it could cause issues. Now I am trying to determine if that action has anything to do with the CEL being on. The codes are P0442 and P0456. The codes have been cleared several times but the light pops back on after a while, anyway from one day to a week later. Smoke test did not reveal any issues. My question is this, can filling up with the engine running cause any physical problems with any of the EVAP components? What would be the most likely problem? I plan on buying a new gas cap, since it is cheap. I do not wish to spend a lot fixing this problem.

Thanks.
 

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I can't think of any reason why filling up with the engine running would cause damage to the evap system. The real concern for filling while the engine is running is that it can cause an increase in static electricity, which in turn can cause a spark at the fuel nozzle (the nozzle is grounded to the pump through the hose, obviously the car is not!).

My guess is that you are the victim of coincidence on this issue.

Good Luck!
 

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Discussion Starter · #3 ·
Thanks for the response. As you can probably guess, the new gas cap did not fix the issue. It took from Friday, when I put the new cap on until this morning (Monday) when I was on my way to work before the CEL came on. On Saturday I made a 2-hour trip, let the car sit all day and then another 2-hours to get back. Yesterday just a few local errands and today I took it to work. I got down the street from the house and the light popped on. Any ideas on best way to troubleshoot?

Thanks.
 

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My guess is that you are the victim of coincidence on this issue.
UNLESS he is one of those folks who chronically overfills the tank by going beyond the first click-off.

If that is the case, it might be more prone to suck fuel into the evap. system if the engine is running.

What do those codes suggest ??

Hopefully one of the Hyundai mechanics who frequent here can provide some help.

In the meantime do some searching on here for threads about evap. system fixes......maybe on different models.
 

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Discussion Starter · #5 ·
Thanks. The codes by themselves suggest a small EVAP leak. Research on this forum and the internet suggest that there could be many reasons, ranging from gas cap issues, to holes in hoses to valves, etc. Since I have eliminated the gas cap as an issue, and since the smoke test, in theory has eliminated a leak, I am wondering what a likely cause would be. It seems some information suggests a canister close valve may be the issue. I am willing to try a new one, they are about a $50 item, but would like some confirmation that is the next place to look.
 

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Hyundai logic in PCM typically runs EVAP self test while sitting still..
You need to clear the DTC from PCM memory, then perform an EVAP self test via GDS and verify repair..

.GOV says motor vehicle NOT ALLOWED to emit raw HC vapors, that is why we run self test on EVAP to verify it secure,,, but at home we free to leave gas cans open all we want.

Simply replacing fuel cap wont do anything to physically erase DTC from PCM memory.. it there till somebody go in and erase it.
 

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Discussion Starter · #7 ·
I guess I should have mentioned that I replaced the gas cap, then I connected a code reader and started the car. The code reader cycled through its routine several times at which point it cleared the CEL. The CEL came back on after a few days of driving.
 

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The CEL came back on after a few days of driving.
Did you inspect the filler neck, looking for a dent or ding that might keep the cap from sealing good ??

Also you didn't mention whether or not you fill past the first click.
Codes like that sometimes eventually mean that the evap. canister has raw fuel in it.
 

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Discussion Starter · #9 ·
I did not see any issues with the filler neck. I can honestly say that in the past I may have gone further than the first click, but with gas costing what it does I usually just stop at the first click, sometimes even before it clicks.

I did notice that once or twice fuel had splashed out of the filler neck, but I think it was with the auto shutoff feature on the nozzle activated and I was standing nearby. It wasn't too recently though.

If the evap canister does have raw fuel in it, will it eventually evaporate? If not is it salvageable or does it need to be replaced? Any thoughts on the FILTER & CANISTER VALVE ASSEMBLY as a potential problem?

Thanks.
 

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That was the cause of my CEL (P0449) and the fix was a replacement of the check valve of the evap canister.
 

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Discussion Starter · #11 ·
It looks like the FILTER & CANISTER VALVE ASSEMBLY, which is under the left rear fender is much easier and less expensive to replace than the canister, which I have no idea how to replace. I may order a new FILTER & CANISTER VALVE ASSEMBLY in a few weeks, unless a better solution is mentioned.

Thanks.
 

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Not going to lie, I fill up while running like 95% of the time. In Florida lately when it is 97 degrees all day and 80% humidity, you don't turn car off unless you run out of gas or arrive at a place you will be at for longer than 20 min... i.e. work/home.
 

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Not going to lie, I fill up while running like 95% of the time.
As long as you are fully aware of the risk involved, I guess that's your call.

You also need to be aware that it probably is ILLEGAL to do that and should a fire break out, your insurance probably would be VOID and you would be on the hook not only for your car but for other equipment that is damaged too.

I sincerely hope that you don't do that with family members in the car. :(
 

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As long as you are fully aware of the risk involved, I guess that's your call.

You also need to be aware that it probably is ILLEGAL to do that and should a fire break out, your insurance probably would be VOID and you would be on the hook not only for your car but for other equipment that is damaged too.

I sincerely hope that you don't do that with family members in the car. :(
typically i fill up to or from work just me driving however, it has been proven that there is less chances of a car blowing up or catching fire than getting in a wreck driving on road.

p.s. it is also illegal to drive any faster than the posted speeds, make right hand turns without stopping completely, and probably half the stuff people do on the road that gets "over looked" because its minimal.
 

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Straw man arguments; meaningless.

It has been proven that none of those other things that you mentioned ever causes your car to catch fire. :eek:
I didn't say that...

I said you basically you have a bigger chance to get into a car wreck than your car has of catching fire due to running your car while filling up. Sorry if my wording was off, cellphone post.
 

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Discussion Starter · #18 ·
Ok so it looks like the canister is ridiculously wedged in a place that according to the service manual require the fuel tank to be dropped. Removing the fule tank apparently requires the mufflers to be removed. Could this really be what it takes to change the canister? Anyone???
 

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I said you basically you have a bigger chance to get into a car wreck than your car has of catching fire due to running your car while filling up. Sorry if my wording was off, cellphone post.
The wording was fine; it's the idea that is "off".

The odds of anything else happening....ANYTHING....has no bearing on whether or not THIS thing is dangerous, ill-advised and illegal. ;)
 

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Discussion Starter · #20 ·
Does anyone have any practical repair advice or are we just going to continue debating whether or not to fill up with the engine running?
 
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