In addition to the built-in capability of the S2, or any modern Audi, to communicate with high tech diagnostic equipment in the dealerships and it's emulators such as VAG-COM, the Bosch Motronic ECU can signal a wide range of stored faults by a simple scheme of 'blink codes'. These blink codes can indicate problems with the engine management system and are an excellent way to diagnose gremlins without the need for a PC.

The only equipment required to pull the blink codes is a 12V lamp or LED and a small jumper wire. These few pages outline how to pull the blink codes from an S2, and what they mean...

Should you wish to install a simple circuit in your car which uses a spare instrument warning light as a malfunction indicator lamp for displaying these blink codes, then follow this link .