^have you tried her recommendation?

 

Yes I am trying it now - disconnected the battery last night. Had to put in a new brake light switch today as well. $3.75 from the dealer....best price on an Audi part ever!

Will let you know when the code reappears.

 

coolant temp sensors can fail sporadically (in my experience), and although it's not exactly the most common thing in the world, it's the reason they come with warranties. I'd definitely look there.

 

Code 2181 has reappeared twice now, since clearing the ECU.

So is the recomendation to install a third sensor?