I remember when this light came on in a VW Rabbit I used to own. I took it to a Sears garage, where the mechanic just used an Allen wrench to press a recessed button in the engine compartment, then sent me on my way. He said it was just a timed light that goes off every 30-50,000 miles, and not to worry about.
Now this annoying little light has come on for the second time since we’ve owned our Mazda Protege. The first time, it quit coming on after I opened and closed the hood while filling the wiper fluid. So I thought its switch was tied to the the hood. But my wife tried that this morning after getting to work, and that didn’t work.
My Chilton’s book doesn’t say anything about the light. Does anyone know if there is a reset switch for my current car? And is the light just a let’s-go-to-a-$40/hr-mechanic-for-no-@!#?@!-reason light?
How many miles have you put on the car? If it just hit 30,000 or 50,000 or some round number like that, it might be a preprogrammed reminder to bring the car in for scheduled maintenance. On the other hand, it could also be your car telling you that it’s seeing something out of the ordinary (you won’t know what that something is till your mechanic reads the trouble codes in the onboard computer, though).
You can get it to turn off by disconnecting the battery for about 10-15 seconds (this clears the car’s onboard computer), but if the problem that originally caused the light to come on is still there, then the light’s just going to come right back on. To be on the safe side, you should probably have a mechanic check it out.
When I bought my dad’s Volvo from him, he said the light came on every once in a while when it was time for service, i.e., based on mileage. When I finally took it in for service, the guys said no, actually, it means there’s something wrong with the engine. By that time, there a LOT of things wrong with the engine…
Believe it or not, the “Check Engine” light comes on when my gas cap is not fully screwed on (2000 Suzuki Esteem wagon). Evidently, air gets into the system and throws the computer into a panic tizzy. I saw proof of this when I brought “The Creature” (my car) into the shop. The first thing they did was check the gas cap - a couple of clicks and the light went out. They recommended I not get a locking gas cap, since the keyhole might allow air in and trigger the “Check Engine” light. I have not had a problem with the light since.
Mind you, this is my second car (the replacement for the lemon). On my first Esteem wagon, “Barbara Jean” (don’t ask), the “Check Engine” light would light quite often, (only 12,000 miles on the car at the time) and it turns out there was a legitimate problem with the engine - bad cylinders. We did get the car replaced after a hellacious fight with the dealership (the “Check Engine” light was on m,ore often than not), hence, my sense of panic with “The Creature”'s “Check Engine” light.
Recommendations: check to make sure the gas cap is on tightly, and check the engine out anyway.
I had the check engine light come on in my odl car, a 93 Ford Probe, twice. Each time there was a problem. The first time it was a BIG problem costing me $1200 (!!). the second time it was a minor problem (a loose hose) and cost only $65, although it kept me from passing my smog emission test.
My Honda dealer told me that the lights are coded. Yellow or orange means “maintenance might be needed, check into this when you get a chance” whereas a red light means “GET THIS LOOKED AT NOW.” I have no idea if that holds for other makes.
When my car has passed a mileage milestone, a “Maintenance required” light comes on, one which can be switched off by a mechanic (presumably after service has been performed). In my old car, the “Check Engine” light meant you could finish your trip (as opposed to pulling over immediately) but you should get to a service station soon to see what was up.
I can’t believe there isn’t something about this in your owner’s manual. Admittedly, I’ve had a hard time finding things in my own manual given the crappy indexing. I suggest getting on one of the usenet forums for VW’s. There will be people on there who have the same car you do and who have memorized their manuals and delight in giving answers. They might be a little smug about it, but you’ll have your answer.
screech-owl: I get the same thing. My dealer said that I needed the screw the gas cap on until I heard about 20 clicks, not the three clicks they recommend in the manual. In their experience, that’s the only way to get it on tight enough. It still comes on anyway if I don’t fill the tank completely at a fill-up.
20!! My gawd, mine won’t go farther than 5, and that’s pushing it! Are you sure it’s not stripped out?! And have they tried to sell you an electric wrench for when it gets over-torqued?
Same thing with my car, a '97 VW Golf. First time I lost my gas cap (I’m a pro at this), I waited too long to replace it and had to have the “check engine” light reset at a dealer. Second time, I replaced it quick enough the light turned off on its own.
My brother the mechanic works at a Chrysler dealership and explained to me how this works when the Check Engine light kept going on and off in my 97 Cherokee this summer. Most newer cars have a diagnostic feature in their computers, along with a spot to hook up a shop’s computer to the car. When the Check Engine light comes on, that means the computer thinks something is not right in the engine. So, you go to the shop, they hook up the computer and the actual problem pops up on the screen, giving the mechanic a clear picture of whats wrong (as opposed to someone calling and saying “its making this noise” or whatever). Nice way to get a $40+ visit from a car owner.
The problem is, the computer in the vehicle likes to err on the side of caution. My Check Engine light pops on whenever the heat index is 100 or above and I’ve been driving for more than five minutes. Oxygen sensor fluctuation, quite common in GM products, according to my brother, nothing major. He also confirmed that some manufacturers, at certain mileage milestones, set the car computer to automatically activate the Check Engine light.
In my opinion, car manufacturers named the light wrong. They should not have named it the “check engine” light. They should have named it “emissions system” or some such thing. Whenever the average joe sees that light, the first thing they do is open the hood and check the oil and water etc. The check engine light has absolutely nothing to do with that. What it does do is signal to the driver that there is something wrong in the emissions system. Modern vehicles are controlled by onboard computers. There are various sensors all over the engine and in fact, the entire vehicle. All of these sensors are constantly sending info to the computer and the computer makes the necessary adjustments so the car can operate. All of these various sensors run within certain perameters. When one of them gets outside of its preset perameter, it turns on the check engine light.
For instance, the gas cap was mentioned. If it is not tightened to a certain tightness, the gas tank leaks fumes out into the air. A sensor in the fuel system detects that there is air escaping from the tank and turns on the check engine light. When the check engine light comes on, it sets a code that a trained technician can get and properly diagnose the problem and then repair it.
In my opinion, the only properly trained technicians are the ones at the dealership. They are constantly going to schools the learn new things and changes.
This is not a plug for dealerships. But think about it. Do you think that Sears or the local garage mechanic has ever sent one of their technicians to any school? No. They may have a plug in scanner to get the code out of the computer, but it is, I think, safe to say that they do not have every set of manuals for every year of every model of car and truck on the road today. And that is what they need to properly diagnose the problem.
I used to be a service writer at a Chevrolet dealer and you would be surprised at some of the things that people have said or done. Some funny and some rather sad.
At any rate, if the check engine light comes on, take your car to the dealership.
I’ve heard the “gas cap” thing too, and I’m inclined to believe that that’s what happened the last time the “Check Engine” light turned on in my 96 Ford Ranger. From what I understand, the Check Engine light is only triggered (in my vehicle, anyway) by sensors in the emissions system. Oxygen sensors monitor the emissions and adjust the fuel-air mixture based on what they sense. If the sensors malfunction, the Check Engine light goes on and the fuel-air mixture is performed according to some preset standard, which is a hair less efficient than letting the system adjust itself.
Of course, I was concerned about the light and took my truck to a dealer, who charged me $70 just to plug in an error code reader and told me I should spend over $300 to replace the oxygen sensor. But, then the light went off the next time I filled up (and tightened the gas cap down properly). Buncha con artists…
I have a '91 Escort, and based on my experience with this car for 10 years, I’m convinced cheezit is right: it is telling you something is wrong with the emissions.
Whenever I drive behind another car whose exhaust smells funny, my check engine light comes on. Every time. Something in their exhaust is getting sucked into my engine and altering my exhaust enough to trigger the light.
The only other time the light has come on was after my timing belt broke. One with only 15,000 miles on it! Boy was I pissed the light didn’t come on before the belt broke. (The coolant pump was leaking on it and softened it.)
The aforementioned yellow/red code (yellow warning light: have this looked at at some point; red warning light: fix this NOW) seems to hold true for most cars I have ever owned.
The modern “check engine” light is connected to the oxygen sensor and thus is more often than not triggered by any sign of improper combustion (including leaving the gas cap off, since that throws off the mechanism for venting fuel vapors); it also is connected to the service computer and yes, it will pester you constantly after a certain point in the car’s lifetime when things just are no longer going to work to factory spec.
Most idiotic use of the warning light: Some Mid-1980s Fords (1984 base model Tempo, 1985 base model LTD). No oil pressure/overheating warning: just one single red light saying “ENGINE”. I know something’s wrong with my engine, it just stopped dead in the middle of the Millard G. Tydings bridge, gimme a better clue.
My old roommate’s ancient Dodge Colt (apparently just a re-badged mid 60’s Mitsubishi micro-car) had a simple odometer-based check engine light that came on every 30k miles.
Now, my 1994 Nissan has an engine management computer that monitors, among many other things: the mass air-flow sensor, the fuel injectors, the throttle position sensor, the camshaft angle sensor and yes, the oxygen sensors in the emissions system too.
Probably the only way to find out what your car’s check
engine light really means is to ask your mechanic, or else
buy the shop manual for the car.
Sometimes the car designers even sneak in clever double-uses for the light. For instance, on the above-mentioned Nissan, there is a manual procedure to run engine control computer diagnostics if you don’t have the fancy computer hookup. It involves turning a screw on the side of the engine control computer’s box, which is in the passenger footwell, hidden behind the floorboard. Once you’ve turned this screw, the engine control computer will flash the “check engine” light in a sequence of short flashes and long flashes. The flashes indicate digits of an error code. For instance, one slow flash followed by three fast flashes would be a code “13” - which is “coolant temperature sensor.” And so you replace the little sensor that measures the temperature in the radiator.
You can see the procedure and a complete table of error codes at:
Until recently, I owned a Holden Camira, Australia’s version of GM’s Opel-designed J-class car, also known in Britain as the Vauxhall Cavalier.
This car had a comprehensive electronic engine management system, including a check engine light that seemed to be repeatedly coming on for no apparent reason.
When it first started happening (when the car was still near new) the mechanics that ran the diagnostics told me one sensor was repeatedly becoming dirty and reporting a fualt that didn’t exist. I soon learnt that the light needed to be backed up by a couple of other symptoms before it was necessary to panic.
If you’re at all handy, you might be able to decypher the error code, but the first step would be to power cycle the car. Disconnect the battery for 5 minutes, then reconnect. Your car may run rough for a while after doing this while it re-learns its idle speed and fuel mapping, but it may clear the check engine light. If it reappears or never goes away, then more extensive diagnosis is indicated.
BTW, definitely check the gas cap too, that is notorious on some cars…
Check BN, Borders or eBay for a service manual, if you’re inclined to read the diag code yourself. I’m lucky in that my Caddy has diagnostics integrated into the dash controls, but usually on other cars it involves a multimeter and a jumper here and there, not too brutal…
On my 82 buick, there is a connector under the dash where you can hook up diagnostics to the ECM (electronic control module). If you short together the right set of pins with a paperclip, the check engine light will flash the error code the next time you turn the key. You can then look up the error code on the internet and get exactly the same info that the car dealer has, minus the fancy video display on their diagnostic terminal.
To clear the error code, disconnect the battery for 30 seconds.
I would recommend trying to get the error code out BEFORE resetting the ECM so that you know what it thought was wrong wit your car.
