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Gentlemen,

may I kindly request a point of view on the following symptoms:

my 2001 B5 was now some 80k miles on it, all services done by the local "stealer" as you call them here on the forum, who has RS4s every week in their service (density of high performance Audis is very high in Zurich, as has been repeatedly mentioned here), so I guess they know what they are doing.

Last service was early August, all fine.

This week I did some quick driving in Germany on the way to/From Munich, both on Tue and Wed. Thereby I had a couple of chances of taking it to what looked like some 280km/h (175miles?) on the clock. Sweet!

Came back on Wed eve, had it standing in town for dinner, drove home at night, next day Thu drove the car into town in morning and back in the evening(8 miles per way). Then car stood from Thu 7pm to Friday 3pm.

on Friday when I drove off, the yellow engine light lights up. Switching off the engine, does not make it go away. Yellow means "should do something about it soon, but not critical" I understand. I drove some 25km motorway (had to do it, important meeting), came same way back in evening after garages had closed.

Left it be all weekend, want to take it to the stealer tomorrow.

any points of view what the problem might be?

The driving I did on Friday with the light on, was all gentle stuff (I HAD to go to that meeting), did not do any stress tests to see if I had lost any power or so.

Reading through the forum this morning, did not see anything really obvious. Some member had problems with coolant system when this yellow light was on. Might be the (ill)famed MAF.

Your thoughts are highly appreciated!
have a most magical Sunday
d.

Wouldn't worry too much about doing damage, the ecu will default to 'limp home' mode and reduce power if it senses something is up, a quick check by dealer/VagCom will show up what has gone faulty, I would guess oxygen/lambda sensor if the car is still running reasonably well.

Thanks "Simple1" for the calming words. We'll see what the VAGCOM will show!
have a great eve
d.

Update: the Audi guys fired up their VAG COM and came up with the following explanation.

There is a system in there that provides additional air flow to the exhaust, in order to warm up the catalytic converter more quickly, so that the quality of the exhaust released to the environment is faster at the required quality level. Now this system is not providing enough airflow, according to the diagnostics.

Consequences: I can drive normally, anything I want. They do not expect any damage to the engine or to the catalytic converter. Only downside is that exhaust is not quite up to standard until the catalytic converter warms up.

Cause: they don't know, have a couple of ideas, want to open up the car (estimate 1 to 3 hours) and see how far this goes.


Anybody here feel competent to comment on this?

Thanks a lot, I appreciate your technical expertise a lot!
d.

secondary injection system is lambda monitored could be those probes there are 4 of them . the system itself is electronic control of 2 vacuum operated valves for the secondary air pump & a relay for the signal from the ecu. all in the rs4 study guide in the download section

the end of the story for those of you that might be wondering:

took the car to the stealer for the appointment made, returned it to me in the evening with "can't find the cause". I went on a 4-day trip of some 750km, starting and stopping several times a day, doing long motorway stretches, and fair amount of mountain roads (yeah!) and city short trips. All this time, no engine electronics warning light on.

Then, come the day where I have returned and the stealer wanted to continue their investigations, while driving there in the morning, ....
... the light goes on. And I go crazy and wild!!!

Anyway, they ended up diagnosing that one valve of the secondary systems sometimes was deficient, ordered a new one, built in,
all works fine since then

take care and happy motoring
d.