Audi Repair: Audi A3 engine electronics warning lamp, handheld scanner, audi a3

Question
The engine electronic warning lamp in my audi a3 is illuminated and the engine does have problems finding the idle speed at startup. The engine speed stabilizes after a few seconds after startup. I also hear a liquid sound from engine when it is running, it sounds as if water is pouring and there is also a clicking sound. I borrowed a scantool and checked for faultcodes but the only stored faultcode was a O2 sensor faultcode (P0139) which was passive. I erased the faultcode but the warning lamp is still illuminated. Any idea what to do?

Thankful for all the help I can get!
/Fredrik

Answer
Hi Fredrik,
Is there actually water leaking from the engine?  If the car has problems iding, it may be that the engine collant temperature sensor is faulty, this is a high failure rate item.  When you erased the faultcode for the O2 sensor, did it come back immediately?  If not, and there are no fault codes but the engine fault light is on, there could be an issue with the ECU.  Are you using VAG-COM or a handheld scanner to check the codes?  Let me know,  Jan