Hi Guys

I have a Audi A4 2.0 sport 2001. I had to replace the body ecu the other day, on the way home from picking it up the car overheated because the fan did not kick in and the oil symbol came up on the dash. Can anyone help and advise me what this is about, is it just another unlucky failure or is it connected to replacing the Ecu?

Many thanks in advance fr your help.