What the hell is a air injection bank and where is it?

i have a 01 a6 2.7t

how much is this going to cost me?

 

I believe you are referring to the exhause gas recirculation (EGR) system. Simply put, a vacuum switch activates a EGR valve (aka Kombi valve, or combination valve) and recirculates exhaust gas to the secondary air injection pump. Bank 1 is your passenger side. You should see a silver round head at the rear of the bank 1 head. Looks like this:


This is your combi valve. Check the vacuum line going into and follow the line for any damage. Many times, a simple vacuum leak can malfuntion the kombi valve.

 

The EGR and air injection are different systems.

The air injection system consists of an air pump (usually at the right front under the fender pannel) that injected air into the exhaust manifold to meet emission standards. The increased oxygen allows the leftover fuel to burn before it exits the vehicle. The combi valves control the air and is activated by vacuum. The most common failue mode is bad hoses - either vacuum or air hoses.

The EGR valve is different. It sends some of the exhaust gasses back thru the intake once the motor is warm to lower NOX.

One takes hot gass from the exhaust manifold and the other adds air to the manifold.