Check Engine Light on 98 (A3) GTI

Just the other day, I started up my GTI, after it had sit for ~3 days and the Check Engine light was on. It seemed to be idling OK, maybe a little rough, but after 3 days of sitting it did not seem abnormal. I decided not to drive it, and have not tried to start it since. I did a search on previous posts. Some posts I found mentioned loose plug wire or loose distributor cap. It's been about 8 months since I did a cap, rotor and plugs (same wires though), so I'm not in the same situation like other people where either they were in need of changing these, or they recently replaced them and did not get a plug wire on firmly.

So, one of my questions is, does the check engine light come in a regular intervals (like the O2 sensor light does in other VWs based only on mileage)? I did just roll over 80k miles probably the last time I drove the car before the light came on.

My next question would be (if the answer to the last one is NO) what are the systems that can trip the check engine light? I am assuming from previous posts that the OBD system monitors spark in some way. Does it also monitor air flow? (like maybe I need a new air filer or have a dirty MAF sensor?)

Well, I'll stop there and see what kind of feedback I get. Thanks. Charles

Reply to
ccp
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If the MIL came on then a problem was sensed by the ECU. You said it felt a bit rough, which might mean the engine misfired for a bit on startup. Was the MIL flashing, this would indicate a misfire. My suggestion just drive the car and as long as it runs normally and the MIL doesn't flash then maybe your engine was having a bad day. If that's the case the MIL should go out in about 3 days.

Reply to
Woodchuck

I just can't find the check engine light on my 1994 A3 GTi. It should turn on briefly when I put the key to the "on" position, right? I've even unpluged the MAF but nothing turns on. What does it look like? Can it be that my car hasn't got one? The ECU does store fault codes - I've checked it with a VAG. (And would love the one ross-tech sells!)

any help will be greatly apreciated.

Bob

Reply to
ghinghis

Thanks. I forgot to mention that the reason I dismissed the semi rough idle was that this was probably the coldest start the car had done in about 2 years - I did not park it in the garage, and the temp got down to the low 20's which is rare around here. So, I figured the rough idle was related to the cold weather. Could the MIL turning on be related to the cold conditions?

ccp

Reply to
ccp

At some point OBD systems would detect a misfire and trigger the light. You car could have had a misfire that was aggravated by the cold weather.

Reply to
Matt B.

Just thought I should post a follow up (it always kills me when people post questions, but then never follow up with how they fixed it...).

Latest is that I drove the car for the first time on Tuesday (since last Wednesday when the MIL came on). I drove about 100 miles, and the light went out after about 75 miles. Car ran very well, and the gas mileage seemed good.

My local shop (Small Car Performance in Tacoma) said that they could pull the codes in about 20-30 minutes tomorrow morning for $34. So, I think I will go ahead and do that just to be sure. Let me know if you guys think I am wasting my money here.

On a separate issue (I plan on searching the archive for this, and posting if I can't find anything) my interior light stayed on all day yesterday while parked and while driving. Finally, it shut off last night when I finally got home for the day. I have had problems with the door switch on my other VWs where the light will not come on, but not where it won't go off. I need to take a look at the manual and see what circuit control the delayed light turn-off feature, because that is what I suspect is at fault.

I hope that my GTI has not reached that point when a lot of things are going to start failing periodically.

ccp

Reply to
ccp

My 99 A4 had the light on Monday. I was out of town for 2.5 weeks and it was not there before. Since they had just replaced the o2 sensor and the CAT converter, I took it back to the dealer.

They just called me and told me there is a misfire in cyl 4, and they blame the Bosh Platinum plugs... funny, I installed them at about 45K miles and the car now is approaching 60K. They wanted $145 for replecing them with 'factory authorized' plugs... and $44 just for the diag...

I will replace the plugs myself, but I am not quite sure it is the plugs....

Reply to
Ricardo Canas

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Reply to
Ricardo Canas

now, if only they'd get those quality-control problems in hand.

Reply to
Frank Zappa

i drive my 97 jetta in the summer months only last spring i started her up noticed a little rough idle and the check engine light, i pulled the code it was something about a random cylinder misfire or something, cleared the code, and it's never come on since (at least from april to november driving

300 miles a week)
Reply to
charles holder

I finally got the codes pulled this morning - multiple cylinder misfires. Car's running fine right now. I am chalking this up to cold weather conditions combined with a vehicle that has been sitting for a while. If the MIL comes back on any time soon, then I'll suspect that something is up.

Also, my dome light is working fine now... go figure.

Thanks for all the input.

Later, ccp

Reply to
ccp

Charles:

Is your GTI a VR6? If so, perhaps the coil is starting to go bad. You may or may not know that VR6 coils tend to crack with age and start shorting out. Actually, the 2.0 coils also have a subtle problem with deterioration, I think. I replaced the coil on my 95 Golf 2.0 and it definitely runs better and gets better mileage.

Bill

Reply to
William Maslin

Bill,

Thanks for the tip on the coil. I'll keep this in mind if the misfires come back. Just for my info, how much did you pay for your coil? (you can email me if you want.) Also, what were the symptoms you had when the coil went bad?

ccp

Reply to
ccp

Well, I used to get intermittent minor misfires on starting in cold or wet weather. In addition, however, the tailpipe went from clean to sooty. Initially I thought the oxygen sensor was going bad. A new oxygen sensor did help mileage and drivability a little, but the new coil really improved the tailpipe situation. I think the old coil killed the oxygen sensor.

I noticed that germanautoparts.com stopped advertizing coils so I emailed them. Mark replied that they had a lot of trouble with aftermarket coils and had stopped selling them and advised me to get a genuine dealer coil. I got one from Timmons VW

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for about $145 with shippping, I think. This was for a 2.0 coil, not a VR 6 coil.

Bill

Reply to
William Maslin

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