Audi A4 engine warning light - what does it mean?

I'm looking to buy a 2006 Audi A4. The engine warning light remains on when started but the car drives fine. What could this issue be? Emissions and/or Cat problem only? Or something more costly?

Vauxhall Corsa engine warning light is on

I have owned a 1998 Vauxhall Corsa for 12 months. It has done less than 52,000 miles and a few days ago the engine management warning light came when I started the car up. The engine also made some strange...

Engine warning light and variable valve timing?

An engine warning light on my Ford Focus led to diagnosis of problems with variable valve timing. I have flushed the oil and replaced the intake camshaft oil control valve. The garage suggested a problem...