I think I didn't tighten my gas cap! :eek:
 

I had to take my car into the dealer because the "service engine soon" light was on.

Turns out it was a problem with the po440 test, meaning either the gas cap wasn't tight enough or there was a small leak in the fuel evaporator. But the problem started right after I got gas, so...

Now, I think even if that WAS the problem and I knew it, I'd still need GM to reset the "check engine" light anyway. But if this happens to anyone, and it's right after you got gas, and the car runs fine.... that is probably why.

Details about car, if relevant: 2002 Oldsmobile Alero, 2.2 liter GM Duratec 4-cylinder engine.

That sucks when that happens. When I worked at a dealer I felt bad when we had to charge a customer to tell them their gas cap is loose. Oh and it can happen on pretty much any vehicle 1996 and newer.

Try taking the leads off the battery for about 1/2 hr. This should reset the computer. A lot of cars have this nowadays, its part of the smog systems.

if you figure out teh problem, the car will reset/turn off the code automatically. AFter so many restarts, i forget the number, without throwing that code, it will automatically clear it for you usually.

Yeah sorry to hear that. And crazybill, here is a time that I actually believe a car dealer :-)

If you look around, usually in wholesale discount stores (I go tmine at National Wholesale Liquidators, but I'm not sure if they're a nationwide chain) you can get a tester to hook up to your engine computer to read error codes. They go for about 30 bucks, and they had them for most makes. It can read and clear the codes for you. If you have a Chilton/Haynes manual for your car, it has a section on how to use a voltmeter and ground wire to read the codes. You don't always need to go to a garage.

I can't speak for anything but VW's, but I think this should be true of most cars.

If you throw a CEL because of a gas cap, after fixing the problem and starting the car 4 times with it running for more than 15 minutes, the light automatically turns off.

Yep, give this a shot first.

Auto parts places like Advance Auto, and Auto zone will do this for free too....the wife has a habit of not tightening the gas cap on her 02 trans am (ws-6) tight enough...

Right after I got my car I was stuck in traffic in Chicago and the check engine light came on. I called the dealer's service department to make an appointment for the next day. The service manager asked if I had just filled up with gas. I had. He said it was probably the gas cap. Told me to retighten it and after so many starts (I think 3) the light would reset itself. Which it did. Saved me the cost of a service call.

BTW - Buick Regal GS 3.8 L V-6

If a dealer is charging you and the car is under factory warranty they are RIPPING YOU OFF!!

Any time a check engine light comes it is covered under the warranty for the diagnosis and cure.

Yea, autozone has a codereader that they will use for free and tell you the problem. Right after I put the longtube headers on my truck I had to drive it with no o2 sensors and no cats to the exhaust shop to get it all welded up, so I was throwing codes left and right. After it was all welded up the light went away after taking off the battery cable for a while, except after driving it for a little bit it came back on. Seeing as I now had my o2 sensors and cats installed, I knew that it wasn't either of these so I took it to autozone and they handed me the reader and said "have fun" basically you just plug it into the OBD2 port under the dash (1996+ vehicles) and hit the power button on the scanner then hit scan and the little LCD shows you what errors you have and what they mean. In my case I was getting a P303, which on a GM vehicle means misfire in cylinder 3, so 15 minutes and a $1.69 sparkplug later I was free to go with no check engines and a good running truck ;). PS on some codereaders there is a reset codes option, but I have been told that this works for some errors but not others, so your milage may vary. With something emmissions related such as a gas cap loose or broken o2 sensor, I'd imagine that you can safely reset the codes.

Oh yeah, one more important thing for anyone that doesn't know... You can usually safely drive short distances with a yellow check engine light on, at the cost of a little fuel economy, but if you ever get a red check engine light stop immediately. Yellow is emissions related stuff, and red is stuff like overheating, and oil pressure loss.

Re: I think I didn't tighten my gas cap! :eek:
 

to reset engine light.....shut engine off push gas pedal to the floor 3 times hold last for 3 seconds let off start car,...should turn off.

We didn't charge them while it was under warranty. Only after it expired.

Cool, thanks. I was wondering about the light and if it would do something worse if it was really bad. What I really need are 2 lights, one that says "you should fix this soon" and one that says "stop driving NOW"

Thanks also to everyone else for all the help. You guys are great!!

note: disconnecting either one of the battery terminals for 2 minutes will be sufficient to clear ANY trouble code stored in the computer's memory. there is no hard disk in there, so, no voltage means memory is cleared.