Freddy_audi

For the past 5 months my 2000 Audi A6 - 4.2L has had the check engine light (or MIL) come on 5 times. Each time I am given the story of how the blame should be placed on regulators who make these sensors react to any small emission leak. Wondering if anyone else is experiencing the same issues.

2.7tDallas

that's crap..ask the SA what the exact DTC's are, and then post them here

tung-sol

I just had this problem ... I do have a vag-com so the direction to head was straight forward, but it's worth a shot on a slow Sat. morning. Doing a search on the secondary air flow DTC read by vag-com, I saw a pic of this vacuum line here on AW that lead me to the solution, but I didn't bookmark it, sorry.

Anyway, pull the engine cover off (four plastic "screws," 1/4 to the left) and look for disconnected vacuum line near the upper right corner of the intake manifold. It's a brown selenoid with a cloth covered vacuum line running from the front of the engine along the right side of the manifold. Mine had shrunk over 1" and had pulled loose. For a quick fix, since it would NOT stretch back, I fashioned an extension from a bit of stiff vinyl and duct tape (unbelievable). I'll get the line replaced next time I go to dealer. If a dealer has looked at your car 5 times and it turns out to be this, shame on them is all I can say. Worth a look.

Good luck.

PaulW

So you think that hose shrunk? I always wondered how it got so small, a few people have had the same problem.

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Here's the pictures, it's almost self explanatory. The pump is driven by a motor in the air box

<img src="http://www.audipages.com/Tech_Articles/enginemechanical/ai1.JPG">


The big diaphrams open up and the pump pumps air into the exhaust

<img src="http://www.audipages.com/Tech_Articles/enginemechanical/ai2.JPG">

There is a small solenoid valve that ports vacuum to the top of the big diaphrams

<img src="http://www.audipages.com/Tech_Articles/enginemechanical/ai3.JPG">

The ross-tech tool can test the component, and I've tested them before, and the air pump is quite loud, probably it.

Freddy_audi

Will do that, taking it in on Wed. Thanks for the help.

tung-sol

someone mentioned the "incredible shrinking Audi vacuum hoses" that appeared to be an audi-tech, I couldn't figure any other explaination either.

jnystr

with my 4.2. My dealer checked it and told me not to worry unless it was flashing. I brought it in for it's routine service a month or so later and they replaced a oxygen sensor under aftermarket warranty ($440) No lights since then.