I have a 2003 diamonte w/ 3.5L. i need to know bank 1 sensor 2 o2 senor is located?

There is 4 senors the bank 1 sensor 1 is located in front of the LH (Drivers side) catalytic converter
Hope this helps

Bank 2 o2 sensor 1 is on the back side of the engine. Simply follow the exhaust manifold nearest the firewall the first o2 is bank 2 o2 1 the next o2 will be bank 2 o2 2. The o2 you see by the radiator is bank 1 o2 1.

I will make this easy for you,assumming your
going to change them yourself

Bank 1 --is on the side of the engine that has cylinder #1
Bank 2-- is the opposite side
Sensor 1-- is the one closest to engine
Sensor 2 -at converter outlet,those don't fail as often

If you have a bad O2 Sensor, your going to change
both (2) Sensors FRONT 2 only
They are the 2 closest to the engine

O2 Sensors- failed or not, get changed,front 2 only
at 100,000 miles.

You need the code read to get the fault code

Upflow = Sensor 1 Bank 1 or 2

Downflow = Sensor 2 Bank 1 or 2

Oxygen sensors are always numbered like this:
Bank 1 sensor 1
Bank 2 sensor 1
Bank 1 sensor 2
Bank 2 sensor 2

Some manufacturers use a kind of shorthand that reads different, but means the same thing:
Sensor 1/1 or O2s 1/1
Sensor 2/1 or O2s 2/1
Sensor 1/2 or O2s 1/2
Sensor 2/2 or O2s 2/2

Bank 1 is always the side of the engine where cylinder number 1 is located and, of coarse, Bank 2 is the opposite side.
On a 4 cylinder engine, there is only 1 bank and it is always referred to as Bank 1.

Sensor 1 is always the upstream sensor (The one located BEFORE the catalytic converter)
Sensor 2 is always the downstream sensor (the one that is located AFTER the catalytic converter.

Hope helps (remember to rate this).

To what? It is located in the exhaust pipe bolted to the rear manifold. Near the firewall

The code will tell you which O2 sensor it is.
The code will point to either bank 1 sensor 1; bank 1 sensor 2; bank 2 sensor 1; bank 2 sensor 2.

From what I remember with a focus, it should only have 2 sensors, sensor 1 will be located before the cat, and sensor 2 will be located after the cat.

This car has a transversely mounted straight six I believe, which is really unusual, but that means it only has one bank, so "bank 1, sensor 1" will be the upstream O2 sensor (between the engine and the cat) and "bank1, sensor 2" will be the downstream sensor (behind the cat).

I think the question is where is the bank 2 precat sensor on the 2.8 v6 passat. I have only found bank 1......????