p0455

[cleenyc99]

First of all I would like to start by saying hello my name is Liam and I'm new here this being my first post unfortunately. I own a small shop in queens NY with a small but grate customer base. I would like to say this site has been grate on giving me some insight into how other shops run and conduct day to day operations. I would like to say thank you for that and I hope to contribute in the future. now let me tell you about my issue with this car.

 

A good customer of mine has a 2001 Hyundai Electra. The vehicle is in grate condition always takes care of what needs to be done. Over the past 3 weeks the check engine light has come on a number of time throwing p0455. we have smoke tested it each time passing with flaying colors the ball is pined right to the bottom. checked the purge valve working grate. so we conducted a evap system test using the versus. now ether the test passes. or the test closes the vent valve and pulls a vacuum on the system then 25 sec into the test the ecu opens the vent valve before the test is done. vacuum drops and sets the p0455. its not the CVV but the ecu itself opening the ground circuit. I've never seen a ecu/pcm fail in this way.

my question to you is why? do think the ecu is faultily?

 

Thank you

liam

[phynny]

P0455 is an evap large leak, I've really only seen this when a gas cap has failed or the large evap line on the tank. The small evap lines won't cause this fault.

 

Oh yeah, another possible cause is a tank that has a leak as it will not hold pressure.

Edited July 29, 2015 by phynny

[ATLAuto]

Agreed. Put a new gas cap on it and clean the opening well.

 

We will sometimes bring a questionable cap next door to the emissions test station (aka a tent in the gas station parking lot). They've got a gas cap tester.

[SMMotors]

It's usually doing that because the ECM is seeing that it can't pull a vacuum. I've sen the canister come apart, plug the purge valve and it can't draw a vacuum so it throws that code.

 

Read your SI, that system uses vacuum, smoke won't help you. Test it correctly and read the code set criteria. Look at your scanner and see what's not within spec and go from three.

[cleenyc99]

fixed it... chased my tail for awhile over thinking it. ended up being an extremely same leak in one of the evap lines. But I feel it's placement was key, right at the tank pressure sensor. Witch on this car is right over the rear sub-frame and has a small rubber line that goes into the top of the tank. Even once I found It I had to look very closely to see the smoke leaking out. The vehicle has been repaired for awhile now no light returned. Sorry for the slow reply completely forgot to post the out come

thanks for the replies

[carolinahigear]

fixed it... chased my tail for awhile over thinking it. ended up being an extremely same leak in one of the evap lines. But I feel it's placement was key, right at the tank pressure sensor. Witch on this car is right over the rear sub-frame and has a small rubber line that goes into the top of the tank. Even once I found It I had to look very closely to see the smoke leaking out. The vehicle has been repaired for awhile now no light returned. Sorry for the slow reply completely forgot to post the out come

thanks for the replies

You weren't slow with your reply.......it was only 11 months!!! But thanks for letting us know!!