00 S4 MAF/Vacuum Problem?

Hi all,
I've had a 'check engine' warning come on intermittently over the last 6 months. My service shop traced the code to either mass airflow sensor, or a
vacuum leak. They reset the warning, but it came back in 5 days.
Does anyone have experience with this problem? I'm told that it will take a new MAF, or even a ECU if there is no vacuum leak.
The car is box stock with the exception of a K&N permanent air filter. 32k miles, and it's had it's 36k service. Its running fine, idling smooth, and pulling strong.
If people tell me that MAFs are notoriously unreliable, I'll just pick one up and install. I'm a little hesistant to let me service shop start poking around - I'm afraid they'll try to sell me a new ECU (computer).
Thanks in advance.
C
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

MAF failures are fairly common across the industry, it's the technology vs the environment, MAFs can see plenty of nasties in the intake air that cause eventual failure. And that K&N filter - if it's the one that uses oil in the filter element - will likely raise the MAF failure rate.
The way to tell if the MAF is the root-cause of the MIL fault is to use a Vag tool or emulator to read how far out of "normal" the ECU is trying to calibrate the MAF. There's an acceptable tolerance range for the MAF. If the MAF is outside of that range, that's when you start seeing the MIL light. You can clear the error, but it'll come back in a day or two or three.
Again, dumping codes will identify the culprit pretty reliably. And Audi had a "stealth warranty" on MAFs for B5 S4, at least. Mine was replaced even though I was out of the warranty period...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Carl, I've lost count of the number of times I've heard "MAF failure" and "K&N" used in the same posting. I've talked to many folks with different MAF-equipped cars with burned out MAF wires downstream from a K&N....my brother included. Go to www.googlegroups.com and search the auto newsgroups for those two things, grab a coffee and start reading..... Cheers! Steve Sears 1987 Audi 5kTQ - K&N now protecting my garage shelf from dust 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi Steve and Daytripper,
I'd like to say thanks a bunch for your advice. I think I'll ditch the K&N, grab a new MAF, and do it myself.
I'll google, and read up.
Again, many thanks!
Carl

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.