P0456 Check engine light - Hyundai Forum - Hyundai Enthusiast Forums

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Old 07-25-2007, 10:37 PM
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Join Date: Jul 2007
Posts: 1
Default P0456 Check engine light

Hello forum members,

This is an awesome site and would really appreciate it if experts can guide me with my cars problem.

I have a 2002 hyundai sonata V6 with 65000 miles.

On thursday (7/19) the check engine light suddenly came on.
On saturday (7/21) took it to Autizone and the guy mentioned P0456 error code and reset it saying probably it must be the gas cap that was loose and tightened it.
Drove about 150 miles. Filled gas after that. Drove another 100 miles approx. and the check engine light came back on monday (7/22).
On monday (7/22) again went to autozone with the same P0456 error code. They reset it again.
This time the check engine light came back on after driving 70 miles.

The car is out of warranty. the hyundai dealers in boston just want to make money and say they do not accept outside codes and they will have to do run the diagnostics themselves and that costs $200 plus the $$$ to fix the problem.

I would really appreciate your opinion.

I am continuing to drive with the check engine light on and this time I shut the gas cap to exactly till I heard 3 clicks and have driven 40 miles and the check engine light is still on.

I really make sure the gas cap is tightly closed and there is no loss in gas mileage or driveablity of the car till now.

Will the car pass Massachusetts state inspection if I just keep driving it?

How can I go about identifying the problem as I know it could be so many things that could be wroing if its not the gas cap.... could be the hoses and seals in the vacuum line... Please advise on the best course of action for a student short on dough!!!!!!
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Old 07-25-2007, 11:52 PM
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Join Date: Nov 2006
Location: Canton/Massillon, Ohio
Posts: 533
Default RE: P0456 Check engine light

With that code you could also have a vacume leak at the engine or your Purge vent solenoid could be defective..one other thing you might want to check out is your Evaporater canister to see if it has a cracked hose or maybe it has become disconnected!

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Old 09-03-2007, 09:53 AM
Join Date: Aug 2007
Posts: 10
Default RE: P0456 Check engine light

Where is the purge vent solenoid? My 2002 has the same condition.
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Old 10-03-2007, 09:49 PM
Join Date: Oct 2007
Posts: 20
Default RE: P0456 Check engine light

A code P0456 is a very small leak in the evap system. 99% of the time replacing the canister close valve solves this concern. The valve is sticking open intermittantly it is very common with the Sonata and Elantra.
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Old 03-23-2013, 05:08 PM
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Join Date: Mar 2013
Location: Las Vegas, NV
Posts: 2
Smile P0456 code

Thanks for adding me to the site. I just saw my check engine light is on, had my neighbor use her diagnostic tool to check it. Can someone please tell them what this means & how I may please fix it; sadly I dont "speak car" yet, in need of some help.

{I own a 2004/05 Hyundai Santa Fe SUV.}

Thank you kindly
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Old 03-24-2013, 11:52 AM
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It's a leak in the emissions control system. Usually it's a loose or faulty gas cap. First thing to try is making sure the gas cap is tight by turning it so it clicks at least 3 times. Then have your neighbor clear the code in the computer. If the light comes back on have it scanned again it see if it's the same code. If the same code comes back then have the as cap checked to see if it needs replacing. If it checks out good, have the canister close valve checked/replaced.

Last edited by NovaResource; 03-24-2013 at 08:09 PM.
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Old 03-24-2013, 05:30 PM
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Join Date: Mar 2013
Location: Las Vegas, NV
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Default P0456 code

Thank you, will check it out & get back to you later if all else fails, i greatly apprecite your time & knowledge!!!
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Old 03-30-2013, 03:21 PM
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Join Date: Jan 2013
Posts: 1
Default Same problem

I had a p0455 (large leak), i put a new gas cap on from Autozone and my CEL stayed off.
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Old 10-18-2014, 08:31 PM
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Join Date: Oct 2014
Posts: 2
Default p0456 my unique fix

I followed much online forum advice after my check engine light came on reading p0456 on my 2004 Hyundai elantra. I started with new hose clamps on the vapor canister connectionsas most where rotted in half but not the issue. then I took canister off, vacuum tested hoses an canister, all good, 100 miles later, light back on. used canister, filter, solenoid close valve, and fuel tank pressure sensor from junkyard(buddy works there)10$. 100 miles later, light came back on. Used purge control solenoid from junkyard,10$. 10'of hose and more hose clamps from pcsv to gastank,6$. 100 miles later, light came back on.
I ended up taking off rear driverside tire and filler cover to expose fueltank vent valve, temporarily gluing, and propping the valve sealed. I undid the pcsv, and blew about 3 cigarettes worth of smoke into the gas tank to check for leaks. No leaks.
after temporarily sealing the snorkel and About 2 cigarettes of smoke into the engine side revealed the leak between the charcoal air canister and the air filter box. 100 miles later, all of my readiness sensors are complete finally and the Check engine light stayed out.
Just thought id post this because I didn't find any reference regarding the intake end and air canister on this code.
2 weeks of troubleshooting this after work is finally over. I guess if all else fails, try siliconing the plastic tube between airbox and air canister directly behind and under the battery.
Hope this brings you better luck than I had...
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Old 10-25-2014, 09:31 PM
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Join Date: Jun 2013
Posts: 18

Replace the gas cap.
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03, 2007, cap, code, elantra, fe, fix, gas, genesis, hyundai, p0456, po456, sante, sonata, tiburon

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