A few weeks ago, for no reason out of the blue, my check engine turned on. I couldn't figure as to why it did; I take it for its usual maintenance, nothing is leaking and I smell nothing as I drive. All my electrical components seems intact and it drives normally, like it first did when I first picked it up. Eventually, the light went away, two days later. I thought it might've been heat, since the check engine light was gone, I just kinda forgot about it. Later, as I was driving down from SF, I got bored so I gunned it; I hit 100mph and suddenly, the light went on. Again, everything was okay, no over heating, no burning smell and all electrical components seemed okay; its just the light turned on. So, today (two days later) the check engine turned off and this occured during mid-day today (it was over 85F today) so its not heat-related now.

Any ideas why this is happening?

Alex

 

Helps if you tell us what car you have

If it's not RX-8 related perhaps you can find help on my site... all the cars are covered there.

 

its a 2000 VW Jetta, not the 1.8T or the VR6, its the other engine. Sorry, I guess I forgot the most important piece of information.

If it was the RX8, I'd be even more upset and probably not drive w/ the check engine light on too.



alex

 

...even Volkswagons??? holy crapola!!! :p

exgf had a neon w/ a bad O2 sensor which caused the same problem (was intermittant as exhaust temp changed... came and went), but was very common for that model series... had a recall...???

anyways, it could be a whole ton of things, and not necessarily engine-threatening... but best to take it to a shop to see what error code the ECU spits out.

 

wakeech you bastard, beat me to it :p

 

go to bed!! it's like 2.00am for you ain't it??? jeez...

 

Working on an assignment :\

 

No way, I bet its this.....

Check the gas cap. Seriously. If it is not tight, the ECU senses a loss of pressure in the fuel system (or something like that) and turns on the check engine light since it can somehow negatively effect emissions.

Take your car to the station, put a few gallons in the tank, and close the cap at least 3-4 clicks.

This happened on my ex's New Beetle. Problem solved after tightening the cap.

Hope it works

 

Yes check the gas cap. I had this same problem. We'll I checked the cap and it wasn't that, but the dealer said the code was for that system. He spent 3 hours looking at the car $50 later and said he couldn't figure it out.

Really peeved me off, because I'm sure it WAS the cap as the light has never came back!

 

even if you tighten the gas cap it still could lose pressure. I remember I had to change a gas cap in my first car (86 honda accord, and it was manual:D ) after doing a smog check. the smog testers told me the gas cap is a bit worned. And after changing the gas cap my check engine light didn't go off intermitantly anymore.

Anyways (off topic) for my current POS car, the check engine light is on right now. It comes on whenever the car engine dies off right after ignition. Happened twice before. First time took it in the dealer and they couldn't find a problem so they reseted the ecu. the second time the light came on and I just reseted it myself. And now the stupid long term airport parking attendant did something to my car and the light is now on. And they broke my radio antenna! Gawd now my looks even more sh**y with an antenna all taped up to my car. Anyways I would reset my ecu again but then I would have to re-set all the radio stations again on my stereo.

A little advice to everyone never leave your car at a cheap long term airport parking. On a side note there is a cute girl working the counter though:D

 

You can buy an OBDII diagnostic checker at most auto parts stores. The plugs are universal, but you'll need a list of codes from a VW dealer or the car workshop manual. Plug it in and it displays the code that triggered the check engine light. Besides the gas cap/fuel pressure issue, many CE lights are triggered by dirty air filters or burnt-out O2 sensors triggering the ECU into thinking the car is running too rich/lean and violating allowable smog parameters. Likely has little to do with performance. If the car keeps running and temp/oil/alt guages are still stable, you should be fine. Keep a roll of electrical tape in the glove box to tape over the irritating dashlight until the code is cleared if you want, LOL!

Funny how people *coughwomencough* pull off and call for a tow truck when a check engine light comes on.

 

On one of my friends cars the check engine light came on so much he just put a piece of tape over it.

 

Autozone stores will read OBDII codes for free. You can use that to read the code and reset it and then run a search on the internet on what the code means.

 

I had a Jetta as a rental car a few months ago shortly after moving to WA. During the week I had it, the check engine light came on and went off 3 times. From the research I did having the check engine light come on was not an uncommon problem for new and fairly new base model VW Jettas...

 

If you know where you computer is (under seat/behind glove box/etc.) you should check it out - both my vehicles have LEDs on the computer that flash the codes. Drive till it comes on then check while still running (- my most recent code said 'bad #2 oxygen sensor, not too surprising at 289k!)
S

 

well, I tried the gas tank thing and that didn't work. thanks for the suggestions, i will try to get to the computer and see if I can get any more information from that. Its just odd that it turned on, and remained on, since I tried to go fast one night.

In either case, I decided to buy an obd-ii/can analyzer; figured it would come in handy for my roomie's g35c and my rx8.

alex

 

Or you could try to download for free here:

http://www.obd-2.com/ve105all.exe

Do go thru the instructions on the help menu to hook up your notebook, you will need a rs-232 ports in your notebook then locate and hook up the other end to your car ECU.

I find the "Dash" menu rather dashing :D

Have fun and good luck!

cheers!!!