Check Engine Light/gas Cap

[gojo]

My wife came home with the car last night and said the "Check Engine " light was on. I took it to Autozone this morning and the analyzer said "emission control failure". the manager of the store said that it usually means the gas cap is loose......and it was. So, its now tight and the "C.E." light is still on.

Do I wait till I fill up again to see if it goes out voluntarily? Or should I disconnect the battery for a few minutes like I used to do with my Lincoln? Please don't tell me the dealer has to get involved with this :)

[92Lex]

You could do either....the best thing to do is to have the computer turn it off by itself though. If the light really bugs you then you could just disconnect the battery terminals (negative first) to turn it off....if the light comes back on you'll know that it's something else. Usually a loose cap would give you a CEL and a code for low fuel pressure...but it could be something else.

[95LS400Bob]

Autozone could have cleared that code with the hand held. Surprised that they didn't.

[gojo]

Autozone could have cleared that code with the hand held. Surprised that they didn't.

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I asked them to clear it. He said they weren't allowed to do that anymore. It maybe just a local store policy.

[molocka12]

How many miles are on your car.

Does it stay on or flash on & off?

If it flashes on & off do not drive it get it service.

If it stays on & you have 60000 miles or more it sounds like your oxygen sensor to me.

[blake918]

What error code did AutoZone give you(so that someone with a repair manual can look it up)? If the cel is still on, unplugging the battery will turn the light off for a few miles, but if there is a real problem, the light will come back and the diagnosing process contiunes! I'd try tightening the gas cap and unplugging the battery first, and if it comes back, you know the problem is elsewhere on the car.

[92Lex]

How many miles are on your car.

Does it stay on or flash on & off?

If it flashes on & off do not drive it get it service.

If it stays on & you have 60000 miles or more it sounds like your oxygen sensor to me.

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How'd you figure it's the o2 sensor? The code that was retreived probally would of been for a biased o2s or air/fuel ratio too rich/too lean if it were the o2s....it's a possibility but most likely not in his case. It's hard to condem the o2s based on mileage alone.

[gojo]

How many miles are on your car.

Does it stay on or flash on & off?

If it flashes on & off do not drive it get it service.

If it stays on & you have 60000 miles or more it sounds like your oxygen sensor to me.

←

How'd you figure it's the o2 sensor? The code that was retreived probally would of been for a biased o2s or air/fuel ratio too rich/too lean if it were the o2s....it's a possibility but most likely not in his case. It's hard to condem the o2s based on mileage alone.

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The car is a '99 with 62,000 miles.

I didn't have time today to disconnect the battery, but I will some time this week. The light is not blinking and seems to be driving fine otherwise. They didn't give me a code per 'se but I did see on the display "emission control failure".

The gas cap was in fact loose so I hope that's it. The last time this happened, the machine did say an oxygen sensor was bad; but not which one. I took it to the Dealer and they replaced the sensor behind the head on the drivers side. A $350.00 affair. Luckily it was covered under the extended warranty.

[92Lex]

I do smog checks and it's not uncommon for a car to fail a smog check just because of a loose or incorrect gas cap. There was probally low pressure in your gas tank causing the code...evap canistor probally wasn't working because of the low pressure. You should do what Blake said and just disconnect the battery and see if the code comes back.

[gojo]

Just a quick post to let everyone know that the check engine light went out on it's own after the next fill up.

Thanks for all the support!