Hi guys. I did some brief work on my a3 last weekend and came across a few things that I'd like to ask about... Firstly, what is the flat plastic object that sits over one of the spark plugs? - See picture. I noticed a gap in the air intake pipe (see picture). Is this normal?! Finally, I replaced the water temp sensor (shown below), in an attempt to remove VAGCOM error code 17704 (Error in Mapped Cooling System (usually temp Sensor or Thermostat)). After doing so, the code remains. Do I need to clear the error to see if I have actually fixed it? Thanks!