1999 Audi A6 Quattro Check Engine Light

Take it by Autozone and have them read out the codes. They will do that for free.

I am going from memory, but I am pretty sure the Audi service advisor told me when the check engine light blinks, you need to get it in for service sooner rather than later.

At the time, mine was on solid, but he was warning me to watch for that.

YMMV.

Actually, it indicates serious conditions that can ruin the engine if driven further. You are suppose to stop and have it towed to get service.

Now, that is taking things to an extreme to protect AoA from owners who are clueless. Some of the conditions are bad but you can drive, carefully, to service and if you are quite sure of what problem is causing the code, and it is not fatal, you can take your time getting service.

It can indicate problems such as total loss of oil or coolant. Obviously, if this is the cause you would coast to a stop and tow it to service.

OTOH, you said that the light is flashing and then stops. You probably have the option of driving to get service rather than towing. The alternative could cost more money that you would want to spend.

What engine is it?

Sounds like a faulty coilpack, you need to read the codes, then it will tell you what is wrong :)

This problem will not be solved without a shop of some kind, and the more you delay solving it the more chances you're introducing more problems, like fouling the injectors and the exhaust system. You need to pull the fault code from the computer before you go stabbing in the dark.