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AudiDoc, Independent Audi Shop Owner
Category: Audi
Satisfied Customers: 6457
Experience:  I've been working on Audis since I was 18 and own an independent Audi repair and performance shop
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2002 Audi A6: 2.7T..Quattro..white smoke were coming..exhaust pipes

Customer Question

I have a 2002 Audi A6 2.7T Quattro with 55k miles.

1- This morning I started the car and excessive amounts of white smoke were coming out of the exhaust pipes, which also smells a bit likel gas (I think).
2- none of the sensors on the car are on, including the check engine light.
3- the car seem to run fine, but after a short 2 mile trip, the engine at idel seem to miss slightly (was in a rush, catching a train).
4- I plan to drop this off tonight to a professional.

1- Any idea what the issue might be, and what the cost should run me?
2- Should I bring this to a Audi Dealership or will a local guy?
3- Is it something that you think might be difficult to diagnose?

Submitted: 7 years ago.
Category: Audi
Expert:  AudiDoc replied 7 years ago.
Are you in a very cold environment currently?
Customer: replied 7 years ago.

Located in NY, the temp is around 25 degrees. It seem to be an excessive amount, normally the car will smoke a bit, but this was leaving white smoke clouds, down the street.


Expert:  AudiDoc replied 7 years ago.
My first thought is that there is a problem or clog in the crankcase evacuation system or PCV system. This comprises of a bundle of corrugated plastic hoses that runs to each valve cover and towards the back of the engine under the convergance of the silver Y-pipe. It's commonly known as the spider hose and it looks like this:


If this hose is cracked or clogged, you'll experience the smoke that you're seeing. I would start by replacing it before going through a huge amount of diagnosis, compression and leakdown testing.

As long as your local guy is very familiar with late model Audis, then I think that's your best bet from a cost perspective.

Also, if your car is an automatic, this hose retails for $180. Labor to replace is about an hour.

If there is any other information I can provide, please post back.

Thank you
Customer: replied 7 years ago.

Thanks for the information, does this type of problem normally happen without the computer realizing there is a problem? Also, is it possible I have a much bigger problem on my hands? Any other recommendations, maybe I should check the car out for other signs to help diagnosis?


FYI, this car is only driven about 5k miles per year and a typical day it is driven between 3 and 4 miles total (train and home). Also, the last time I used was friday night and it sat all weekend, also just filled up the car with gas.

Expert:  AudiDoc replied 7 years ago.
All very good information. Yes, I've seen 2.7T cars run with poorly-functioning PCV systems for 1-2k miles before setting a lean-running code. These cars are pretty solid from a mechanical standpoint, and I typically only see internal damage from either lack of maintenance, or ultra-high horsepower modifications without good supporting strengthening.

Also, your mention of short trips makes me think even more that you've got a clogged PCV system. See, the engine never reaches, or seldom reaches oil temperatures high enough to burn off condensation from the inside of these plastic hoses. What I'm speculating you'll find inside of them is similar to what you would expect a clogged artery to look like, but the buildup will be tan and sludgy in nature.

And finally, a good quick test to see if the system is functioning is to remove the oil fill cap when the engine is idling. There should be a very slight vacuum that holds the cap on even when it's in the unlocked position. If there is no vacuum or even a little pressure, then your PCV system is definitely at fault.

Again, if there is any further information needed, feel free to ask.
AudiDoc and 3 other Audi Specialists are ready to help you
Customer: replied 7 years ago.

Thanks, I'm accepting your answer. I might have one other question later, if that is ok, when I get home tonight?

Expert:  AudiDoc replied 7 years ago.
That's no problem at all. Believe me, I know 2.7T's well, as there are two in my family (02 Allroad, and 00 S4), and another 40 or so that I work on.
Customer: replied 7 years ago.

OK, so I took a few observations:


1- the car was smoking when I got home last night and started.

2- when I drove home, it seemed better than it was that morning.

3- No issues with the car missing or running funny.

4- when I got home, after 1.5 miles, it seem like less smoke was coming out but still smells

5- check the oil cap and no vacuum

6- this morning still not a lot of smoke, and seems to smell much less than yest



Could the car has gotten bad gas (just filled it before this issue) in the lines?

Is there a way to treat a clogged line(btw, I alway use super, which I thought would help with these issues), without a part replacement?

Do you think I should take a long ride to help clean it out?

If it stays as is, should I still have it checked out?


Thanks again



Expert:  AudiDoc replied 7 years ago.
Good information and good questions.

I'll answer them below:

Could the car has gotten bad gas (just filled it before this issue) in the lines?

- This definitely does not sound like a fuel-related problem, but if you want to be sure, it can't hurt to add a bottle of dry gas.

Is there a way to treat a clogged line(btw, I alway use super, which I thought would help with these issues), without a part replacement?

- For this particular problem that I'm speculating, different types of fuels won't affect it either way.

Do you think I should take a long ride to help clean it out?

- It's possible, but in most of these cases that I've seen where the PCV system is restricted, it's best to just replace the hose, especially considering that you don't find any vacuum under the oil cap.

If it stays as is, should I still have it checked out?

- That would certainly be best.