The check engine light came on in my car while I was on the freeway. I was only a couple of miles from home, and the car seemed to be running fine so I drove it the rest of the way here.
There doesn’t seem to be anything heinously wrong, no weird smells, no leaks, it’s not running rough or anything, but I did notice that the little gas door thingie was open a half an inch, and my gas cap is missing.
I filled it yesterday. It’s entirely possible that I drove off without my gas cap, but I think I would have noticed the door being open this morning when I walked to my car. I dunno.
The car is a 99 VW Passat. I bought it used a year ago, and it didn’t have the manual with it.
So, I’ve got a question for my fellow VW owners (who presumably still have the manuals to your cars) - do you know if the check engine light goes on just for real engine trauma, or does it go off to indicate big regular service check ups too (my Volvo used to do this)? Could it have gone off due to my lack of gas cap, or the door thing popping open?
I just had the car serviced a couple of weeks ago, and everything was fine. It could be that somebody stuck something in my tank while I was at my appointment, but then the car should be running badly.
Yes, I’m going to call the VW people, but I’m not anxious to spend $100 for a diagnostic so they can tell me my gas cap is missing or my wiper fluid is low.
First thing to always check is the gas cap thing, and you mentioned this.
Let’s say no one vandalized your car.
Then, what are the odds of leaving the cap off a little AND something like a sensor going at the same time?
You almost have to assume it’s cap related. If you get it serviced, tell them that you drove with the cap off causing the light to come on. It might just have trouble resetting itself, and the opp is just sitting their for a dealer scam job.
My wife’s got a '99 Dodge Intrepid, and she once forgot to tighten the gas cap all the way. Sure 'nuff, the check engine light came on. But despite tightening the cap properly, the light never went out (even after a couple of days of driving). She had to take the car to the dealer to get the light reset. That’s happened more than once, with the same result; now, whoever fills the tank tightens that gas cap like nobody’s business. I hope your Passat doesn’t behave like that, but it might.
Thanks guys! It never occurred to me that something this stupid really would set that light off. Now I just find it odd that the thing let me drive 60 miles before it went off. Whatever.
I finally got through to the VW service guy. He wanted me to come in to check the diagnostic code ($85) just in case, but finally admitted that the gas cap is the problem and that it will probably take a week of normal driving (200+ miles) for the light to go out.
Beware of the “check engine” light. It may be a scam.
In 1989, a red light on the dashboard of my 1976 VW Rabbit lit up which said, “EGR”. According to the manual, this meant “Exhaust Gas Recirculation.” This sounded particularly horrible. Images of driving along and dropping dead from carbon monoxide poisoning filled my head. I immediately rushed to an auto repair center to have them check it out.
And do you know what the mechanic said? He said that the EGR light was a light that was programmed to go off every 15000 miles to remind you to get your car maintenanced!
VW might have done a similar thing with the 1999 Passat’s “Check Engine” light.
“EGR”? That’s probably the smog emission thing. Light is useful to let you know that its time to get it
changed (every 15000 miles)----I’d wait & see what the smog guy has to say about that.
Now that sounds familiar! I had a 1984 Rabbit, 10 years old, with a light that came on like that. Red lights shining on the dashboard are annoying enough, but when it’s a light specifically designed to prod me into bringing the car in for service…Good God, don’t the mechanics think I have enough sense to do that on my own? :mad:
1977 VW Dasher - same thing. I learned how to push the little button under the hood myself and shut off the EGR light. I had my Exhaust Gas Recirculation valve replaced as a matter of routine maintenance, but not on VW’s schedule.
On the newer cars, I believe the gas cap forms an integral part of the fuel pressure system. With it missing, I think something happens to either the fuel return system or the emissions control system due to having insufficient pressure in the tank, thus the light comes on.
I’m a Broadcast Engineer, not a professional mechanic. My old Jeep doesn’t use all this fancy stuff, so I could very well be talking out of my hat here.
The reason for the check engine light to come on when the gas cap is left off is fairly simple. The government requires it.
It does no good for the government to require the car makers to meet stringent evaporative controls, if they can be completly rendered moot by the driver leaving off the gas cap. So you get a check engine light. Think of it as an emission stupidity tax.
Yes, the regs allow the light to be turned off via reqular driving and the system seeing no faults. However, the diffculity of this varies from car to car. In some systems the drive cycle is very diffcult to achieve.
