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2005 Hundai Elantra Evaporative Emissions Large Leak

My 2005 Hundai Elantra has check engine code p455 - large leak in the evaporative emmission system. I’ve changed the gas cap (Hundai dealer cap) and the purge valve. Have also examined the charcoal cannister and it’s valve. Both appeared secure and functioning properly. The access panel to the fuel pump appears to be tight. Are there any other “home remedies” that I should try before taking it to the dealer for repair? Thanks, - Turtle8

Since you know where the canister & the purge valve are, did you follow all of the vacuum hoses that lead to and from them? Chances are that you have one disconnected, broken etc. You’d need to follow them all the way to the tank in one direction and to the intake connection in the other.

If you decide to take it to someone you don’t need to take it to a dealer. Any local, independent mechanic should be able to handle this more reasonably.

2 years and a boatload of cash, still this error persists.
At best, a new part has it pass inspection, and then within 4 days, the check engine is back on with the same error.
Dealer says all the mechanics look fine. That it “may be” electrical, that it’d be approx $300 to run electrical test. So, hundreds and hundreds of dollars in repairs, and here I am again, with P455 and annual inspection due.

Opening the system to install a new part airs it out - gets the excess HC out of it. After the system is closed for a few days, the HCs have built up and that triggers the CEL. So far nobody has correctly diagnosed the problem.

In some places you get some leeway on annual inspection if you show that you’ve paid to get it fixed and are still trying.

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Sorry, I’m auto mechanics illiterate. What is HC?
My state gives someone a few days to fix a failed inspection, but they do expect it will be fixed.
This is a ludicrous cycle, spend hundreds, to have it “fixed”, for a couple of days. The car is hostage to this, as the light is pervasive.
Late this past winter, for the first time in two years, the light turned off when the gas was below 1/2 a tank. With the warm weather, the Check Engine is back on, and inspection is due this month.

Hydrocarbons. Mechanics now have a “sniffer” tool that senses unburned hydrocarbons in, say, the plumbing of the fuel/emissions system, or at the tailpipe, or in the cooling system.

Yes, this is a 2005 model, which means that it cannot store permanent trouble codes, and it is allowed to have one monitor show “not ready” and still pass emissions. As long as the car runs and drives fine, I would spend no more money trying to fix this problem, which is really only a problem for purposes of passing emissions.

What I would do instead is buy a decent low-cost OBDII scan tool, such as the Konnwei KW850 which is the one I use. I would then go to a gas station and top off the fuel until you can put no more in, then go home and disconnect the battery for a few minutes to clear all codes. Then reconnect the battery and drive the car for a few short trips, making sure to allow the engine to warm up completely. Keep the fuel tank as close to full as possible, while checking periodically with the scan tool under its “I/M readiness” function to see that all of the monitors have run, except for the evaporative emissions monitor. Now, top off the fuel again, go to the emission testing station, and it will pass. Of course the light will come on again once the fuel level comes down, and the evaporative emissions monitor runs, but who cares at this point?

Like shanonia posted:
Find out what your state authority requires you to pay in repairs. In New York State for example, one can get a waiver if cost of repairs has exceeded 450 dollars.

My state doesn’t have a fixed cost amount for waiver. Waiver request requires the person to say they don’t have the money to fix it. I will likely write saying this error has been pursued for 2 years and my nearby mechanic has said, there is no definitive answer to large evap leak, it’s an open ended error message.
I have a call in to Hyundai. Given this stopped went below half a tank during winter months, they should know exactly what tests are kicked off in that tank level range. Last time they directed me to the dealer, before the 1/2 tank incident occurred, so maybe they’ll be more pro-active on this this time.
Because inspection is due, I’m pursuing both the waiver and Hyundai conversation.
My favorite mechanic says ditch it, it’s old. I think that’s nuts, for a perfectly operating car, that has one little light going off.

You are replying to the OP, who started this thread almost 10 years ago. I imagine the issue has been resolved, one way or another.

Yes the original poster likely resolved by now, but thousands upon thousands have the same issue.