Another Check Engine Light

Howdy Folks,
My wife was driving my car last week for one of the few times she ever drives it. Called me to tell me that the check engine light was on. She did her investigative work by looking in the owners manual. We all know that the light can come on for any reason. So that was no good. However, I thought that was cute that she would try to troubleshoot.

Anyway, I told her to park it until I got home. Once I was home, I started the car and the light was still on. Got an appointment today at the dealership. The report it is a faulty canister close valve. Not sure what that is. But the car is supposed to be okay to drive. Will take two days to get the part. We'll see.

By the way, 6,400 miles on the vehicle, since Dec 2008 with no complaints. Until now!

From my experience, unless something is noticeably wrong, the check engine light is usually emissions control related. I've had it come on when the gas cap is loose, the air filter cover is not snapped down, etc.

But yeah, it's not as intuitive as you'd might think it could be with computers and LCD displays. Other than to preserve dealer diagnostic fees, I'm not sure why they couldn't display the OBD code in English.

That is why I so wish our Genesis was fitted with OnStar. Just touch the blue button when the check engine light comes on and the advisor will run a diagnostic check and within a few seconds tell you whether it's anything to worry about and, in some cases like the loose fuel cap, how to fix it. Oh, and you get an email from the car every month telling you how all the systems are doing, when to change the oil, what your tire pressures are etc. etc.

MartinC said:

That is why I so wish our Genesis was fitted with OnStar. Just touch the blue button when the check engine light comes on and the advisor will run a diagnostic check and within a few seconds tell you whether it's anything to worry about and, in some cases like the loose fuel cap, how to fix it. Oh, and you get an email from the car every month telling you how all the systems are doing, when to change the oil, what your tire pressures are etc. etc.

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Much needed reminders for GM cars?

Not to be a wise-a$$, but my reminders:

1) Three clicks on the gas cap or keep turning.

2) If 5,000 miles since last oil change - time to take the car in for the next Mobil 1 oil change.

3) Genesis has low tire air pressure warnings - my wife has used this feature twice. Both times from nails etc. Else, my $5 tire pressure gauge works fine.

Actually, I think that all car will eventually have telematics like OnStar or Sync. GM was smart in that I think a lot of people are more loyal to OnStar than to the vehicles they come on.

Hyundai has an OnStar like service in Korea, and they're in partnership with Microsoft for a Sync like capability in future cars.

As long as the Malfunction Indicator Lamp (MIL, also called "check engine light") is not blinking, it's safe to drive the vehicle. As told to me by a Hyundai service department manager. That is true for many vehicle brands as well, not just Hyundai.

The original intent of OBD was to make cars monitor their own emissions systems and indicate when something could possibly lead to above-normal emissions - not that the car was in fact "grossly polluting." California spearheaded this type of stuff... and it was Cali that said the light had to imply/say "check engine" rather than "check emissions." Thus the little engine icon used by most cars. Why? Cali figured most drivers would ignore a "check emissions" warning until it was time for their next smog check; a possible delay of up to two years. Cali figured "check engine" would scare folks into getting the car into service bays quickly. Of course most folks know the light "crys wolf" often so they continue to ignore it unless they can feel the engine vibrating, running rough/poorly, etc - i.e. they can tell there is a real problem. Also, the OBD standard proposed by Cali was supposed to REPLACE the in-car methods used by many manufacturers at the time (e.g. Chrylser had a turn the ignition key on-off-on-off-on-off-on deal at a certain rate, then the dash check engine light would blink the code numbers) to make it impossible for home mechanics to fix things themselves - Cali assumed home mechanics were all "bypass the sensor or rig it so the light goes out" type of people: i.e. guilty until proven innocent. Thanks to modern integrated circuits though, the OBD readers ended up dropping on price considerably so Cali lost out on this one. To be fair, one thing Cali does to help out the car owner: Cali mandates a long emissions warranty so getting the car to a dealer/shop to fix the check engine light shouldn't cost owners anything for a long time... though Cali car buyers often get hit with a surcharge on the car sticker price to pay for this long warranty. Other states have since adopted that long emissions warranty requirement.

When OBD was first proposed, many small auto repair shops cried out. Manufacturers had been installing various methods to "read out codes" in their vehicles - and each manufacturer did it differently. Some required special equipment... which was a cost issue for small shops servicing several auto brands. So they said "if you're going to force that on us, at least make all manufactures use the same test gizmo so we only need to buy ONE." Thus OBD. Two bad the spec was screwed up in one detail: the method of signalling the codes (the electrical part of the spec) allowed two different technologies so readers had to have both ==> more cost. Now there is a third signalling method to keep up with the "networking" used in cars these days. OBD also expanded to OBD-II with more codes and more things being monitored - and a "smarter" code reader was needed; and one that could handle all 3 electrical protocols. Cali even proposed an OBD-III a few years ago: when your check engine light is ON, the ECU would use cell-phone technology to phone CALIFORNIA (not the vehicle manufacturer) to tattle-tale you; then you'd have 30 days to get it fixed at a Cali licensed shop that would report back to Cali "it's okay now." After 30 days? Cali would tow your car away or revoke the license/registration. That got shot down by public outcry a few years ago.

As for the original poster: "canister close valve" sounds to me like the "purge valve" on many cars. To absorb gas fumes evaporating from the fuel tank and intake manifold, cars have been equipped with charcoal canisters for decades now. Just like Odor Eaters for your shoes. When off, the valve connects the canister to places that might have gas fumes so the canister absorbs those fumes. Then, once the engine is running (and typically warmed up too) the purge valve changes to allow engine vacuum to suck on the charcoal canister, sucking out the trapped fumes and clean the charcoal. It's a passive emissions device. The entire fuel tank/fuel pipe assembly should operate at atmospheric pressure or a slight vacuum (as the engine drains the gas tank); when sensors don't "see" this vacuum accumulate as you drive you get the common "check engine" light for a bad/loose gas cap. Gas caps have a spring-loaded valve to let outside air into the fuel tank (to replace the gas you've burned) once the vacuum reaches a certain level... but this gas cap valve should NEVER let pressure escape from the fuel tank - that would mean raw gas vapors are going into the atmosphere. Instead, those vapors should go to the charcoal canister. If the system never measures vacuum in the tank or fuel hoses, it assumes there is a leak somewhere - including the cap - and that sets the check engine light. Most of the time it is in fact a loose gas cap or a cap with a busted rubber gasket/seal.

mike c.

What a write-up mikec! Thanks for the info. Of course they didn't tell me what the cause was, just what they thought the fix would be. We'll keep our fingers crossed that this does correct the issue.

99% you either did not properly tighten the gas cap or you "topped" off the car and flooded the canister close valve system. Let us know what the dealer says.

Sayantsi said:

99% you either did not properly tighten the gas cap or you "topped" off the car and flooded the canister close valve system. Let us know what the dealer says.

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I top off the car every fill-up, just as I've topped off every car I've ever had. Never had problems.

ctrcbob said:

I top off the car every fill-up, just as I've topped off every car I've ever had. Never had problems.

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I assume that's because there's a difference between topping off and topping off to the point that gas is coming out of the tank. I see people do that about once a month at the gas pump.

Theres also the difference in fuel systems - a modern car is much more sensitive than even a five-year old car on the fuel system being sealed, much less a 10 or 15 year old car with no system at all.