Questions about parts (with pics)


Registered User
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?



The Clar!! it mouves!!!
The flat bit on top of the plugs is a vacuum chamber...... see threads on N249 removal and this will delte this and improve your dump valve the detriment of overboosting

the gap im unsure of, although id guess the MAF is off a different model if the gap goes all the way through

and the code would need clearing though vagcom....simple enough to do if you buy a £10 lead off the bay ;)


The gap isnt a gap....the seal on the MAF is further into the airbox. Dont worry about it.


Registered User
Thanks for the info guys. I ran VAGCOM when I got home from work and cleaned the codes. I took it for a spin and it felt really smooth and pulled well. Will re-check for codes tomorrow.

1 final question on part identification...

What is this, and should it be sticking out as much as it is?


There is a ticking sound coming from it (or somewhere right by it). It doesn't seem to want to be pushed in more...


Like A Thristy Dingo ;)
I noticed mine gives off a tick the little ******, i think its a carbon chamber that reuses fuel. Im prob wrong though.


VCDS Map User
I asked a Audi teck about this he said "ticking is good, you will hear it now and again"


Registered User
I was concerned about this and did some research, turn out it is omsething to do with charcol burning


335D Driver :-)
Its the charcoal collection chamber, and will, and is supposed to tick.

It captures fuel vapors and prevents them from escaping to the atmosphere and then stores the fumes and recycles them to the fuel tank or engine intake for combustion as needed.

The long and short of it is that it helps to protect the environment and improve fuel economy, allegedly.

Annoying though it can be, ignore it. It's fine.


They called him mellow yellow.
The last pic you showed is the vent pipe from the fuel tank to the charcoal filter & its quite normal for it to stick up like that. Also your temp sensor fault code for "mapped cooling" is usually related to a temp sensor built into an electronic thermostat housing, the sensor you have replaced is the G62 which usually puts up a differant code.