2001 Jetta VR6 MIL Light

Just an update. We brought the car to autozone to have them tell us the error code and they said that it was cylinder 4 had missfired so no big deal. They reset the code and we started driving it again and all seemed fine. When leaving work that day the light came back on and the car was running ruff (light vibration and lack of power that it used to have) and something still seems wrong. The person at autozone said that it could have been bad gas. Could this still be the case? Any help would be appreciated. thanks.

A friend of mine had a similar problem with his Jetta. I asked him what gas he was using and he said regular. Looking in his manual it clearly calls for 91 or higher. It also says that on the fuel door. He said, "yeah, I knew that...but come on, that doesn't really matter, does it?"

The VR6 engines need premium fuel, so use that. It's possible that you purchased fuel labeled as 91 octane but was actually midgrade. This is unlikely to cause a problem, but if you bought from the same place a few times, the knock sensors could have detected premature firing and adjusted the timing accordingly.

I try to buy from larger fuel companies because you generally know what you are getting. Chevron, Shell, BP, Exxon....or whatever the labels are in your area. Citgo is one to avoid as is Marathon. QuikTrip is ok if you live in area they operate in. Believe it or not, QT is a top tier fuel despite being marketed as a cheap gas.

Thanks for the response. If it is bad fuel would finishing off the current tank filled with regular fuel and then trying premium do any harm? We have only had the car for around 4 months or so and had been using reqular gas in it without issues or so we thought. Can you tell me what it means when the check engine light flashes. I see a number of people saying that as long as your check engine or MIL light does not flash. What happens or what does that mean when it flashes? Thanks for the help.

Go ahead and finish the tank of regular. There's not a lot you can do now except switch to premium and go from there. If you've been running regular fuel in the VR6 for 4 months, it's likely the knock sensors adjusted things and your switch to premium will cause things to switch back. This will most likely result in cylinder misfire recordings in the onboard computer. After a few tanks of premium, you should be fine again.

Usually the simple explanation is correct. When you say flashing do you mean the light blinks or does it flicker? Some models are capable of dumping the OBD error codes by blinking the MIL. But if it's a flicker, it's probably just an electrical short.

Blinking the error codes is not something that the car will do on its own, so I'm going to say it's probably a short. If there are error codes, the light comes on. It only turns off when you erase the codes. It's a pretty simple indicator.

No problem. One request: when you followup, keep the original thread in the message so the context is easy to follow. I hate to play USENET police, but sometimes people just aren't aware. There are a lot of FAQs online that discuss accepted USENET etiquette.

That is what we will try. I appreciate your input. I suppose we will have to have the MIL reset so it turns off or will it just shut off when the problem resolves itself? The light would come on steady for a short period of like 5 minutes and then go steady again. It didn't seem consistent. I will try and remember to post back the results of the premium fuel try. Thanks again.

If an error code is recorded, it has to be cleared for the light to go out. Some conditions are checked by the onboard computer system and if normalcy (heh) returns, it will remove the code. And some codes are recorded at boot time and then removed when you start the car again.

Cylinder misfire error codes will have to be cleared for the light to go out. If you live in the metro Atlanta, GA area, I can help you with this. I have a VAG-COM interface.

Are you sure it's the MIL? It's possible that a warning is triggering the light on and off.

Good luck.

Also, you forgot to keep the message thread intact. Please do this as it makes following usenet threads much easier. I suppose it could be your news client doing this, but I'm not sure. I know some web gateways for usenet really screw with your reply. The Netscape and Mozilla readers (Netscape Mail & News, Mozilla Thunderbird) work fine as do Pine, slrn, tin and many others.

Thanks again for the response. Unfortunately I am not in the Atlanta area but I appreciate the offer.

MIL, isn't that the same thing as the check engine light? I must apologize as I don't know much about this sort of thing if you haven't been able to already tell. What do you mean keep the thread intact? Do you mean include the original response in my response? If that is the case, i can copy/paste it into my response and respond accordingly if that would be easier? I am using google groups to browse/respond so I am not sure if that is the reason or not?

When you said "That is what we will try.", you should quote at least what "that" is that you are referring to.

I think "keep the thread intact" was not good wording, in that I don't think he wanted to encourage you to quote portions that are not relevant to your follow-on.

I doubt that using good regular would cause the symptoms you described earlier. However if you just wanted to raise the octane of the fuel in your tank, it is OK to top the tank off with super-premium. The resulting octane of the mix will be somewhere in between.

While I don't have any useful troubleshooting info to offer, I doubt that your symptoms are caused by fuel. Not impossible, but IMHO not likely.

MIL == check engine light. Yes.

Sometimes people see warning lamps come on and off and think it's the check engine light. It may be another light (like the ESP indicator in my VW only comes on when ESP is in use). Just trying to rule out the simple things.

Google Groups is most likely the problem here. *sigh*

Like I said, I hate to play Usenet police, but it's just difficult to follow a thread for a few days if previous content is removed. The web gateways for Usenet don't really make this easy.

A good newsreader will paste the message in your editor when you tell it you want to followup. You can then reply under the text as you would a typical email. Unfortunately this trend seems to have died off as more and more people use web email frontends.

Let me see if I can find some good links for usenet etiquette. I know this is entirely off-topic for this group, but bear with me...

I can't seem to find any good ones anymore. Here's one:

The guidelines I wish people would follow:

1) Use text only (not HTML formatting). 2) Markup for bold and italics are done with old-style typesetting marks (*bold* and _underline_). 3) Place your reply under the sentences you are repsonding to. Whatever you are replying to should be prefixed with some sort of quote character (typically '> '). See my messages for examples. 4) Keep your lines under 80 characters. 5) Be brief.

And of course you can see I've broken my last one here. The guidelines are to promote maximum readability across all platforms and so that threads make sense when people refer to them years later (through Google Groups, no less).

Right, I did not word that very well. With regards to quoting, I want people to quote what makes sense to the casual reader. Enough so that you aren't lost when reading it.

Posting a followup that quotes the original as a gigantic blob and your reply is another gigantic blob below that is not very useful. But now I'm starting to sound like Usenet police.

This is very good point. My suggestion was based on seeing your post and that it was similar to a friend with the same problem. There are a lot of other factors involved...changing the fuel is a simple first start.

Mixing premium with regular is how you get midgrade. This is how tank farms produce midgrade fuel for stations. They mix regular and premium and add the 11 herbs and spices for that particular brand (Techron for Chevron, IQ for QT, etc.)

Flashing light means engine is missing and could damage cat. Bad gas, hog wash. They why aren't the other 5 cylinders missing since it all the same gas to all the injectors. You may have a faulty coil pack... so e-mail me and I can tell you how to diag the issue. I also have a new coil for sell at greatly reduced price for your car.

I don't think changing to premium fuel will fix your problem I own a 99 GLX

2.8k Passat which calls for premium fuel, but only run the 87 octane stuff due to cost and being a conservative driver. I never had MIL come on yet. The Germans are smart and have knock sensors on their engines. Your has 2 knock sensor which monitor the engine for ping/knock. If it "hears" it the timing is reduced until it stops and if no knock/ping is heard within a certain time, the timing is returned to normal. Running premium fuel to get the max performance out of your car, but if you drive like I do then lower octane fuels work fine.

Yep, check the coil pack. I have a much older 94 VR6 Passat, but had very similar issues when my coil pack went south. Ran like a dog, with no power. Of course, one cylinder wasn't firing. Could also smell raw fuel in the exhaust. If that is the case, fix it NOW, before dumping all that raw full in the exhaust damages the cat.

BTW, if it happens when its raining, or very damp, versus not at all on a very dry day, then it is extremely likely the coil pack is the issue. If you, or someone you know is even the slightest bit mechanically inclined, it is an easy DIY replacement.

Also, if you buy your pack from an secondary parts dealer, do NOT accept a unit with the idenfying info ground off. I got one from a local parts dealer like that, and it only lastest 6 months before the epoxy sealing material cracked and I was back at square one. The OEM manufacturer (Telefunken?) must have made a bad batch, and they must have known it, since they ground off their identifying name and numbers, but instead of properly destroying them, they leaked them out the back door to the secondary market. Should have known when the local parts places quoted me $150 versus the $300+ from the dealer.

If Woodchuck has a good part, for low dollars, then I would suggest you take it. He has been around the list for a while.

David Glos