Is bank 2 sensor 2 a left or right and what is the code number to buy ?

Notes in relation to bank numbers
•Bank 1 always refers to the group of cylinders which includes No.1 cylinder.
•The majority of small engine European vehicles will only have Bank 1 sensors fitted (i.e. 1 x Front & 1 x Rear).
•An inline 6-cylinder engine may have cylinders 1, 2 & 3 referred to as Bank 1 & cylinders 4,5 & 6 referred to as Bank 2.
•V configured engines would normally have Bank 1 & Bank 2 sensors, with again Bank 1 referring to the group of cylinders which contains No. 1 cylinder.
Notes in relation to sensor numbers
•Sensor 1 always refers to the front / regulating (Upstream / Pre-cat / Upper) sensor.
•Sensor 2 always refers to the rear / diagnostic (Downstream / Post-cat / Lower) sensor.
N.B. Some larger capacity vehicles may have 2 rear / diagnostic (Downstream / Post-cat / Lower) sensors on the same bank, which may be referred to by EOBD codes as sensor 2 & sensor 3. Sensor 2 would relate to the rear sensor closest to, or in the catalyst, with sensor 3 relating to the rear sensor furthest from the catalyst.
Notes in relation to position
In some catalogue entries, a sensor will be listed as fitting in left or right position. This is always taken from the point of view of sitting in the vehicle (i.e. For UK RHD vehicles Right = Offside, Left = Nearside).
Correct identification of the relevant oxygen sensor is more important than ever as many vehicles now may have devices such as temperature, pressure and NOx sensors fitted to the exhaust system in addition to the oxygen sensors.

Hi Jesus, Im AL the owner of Big As Auto Repair.

If you have a 4 cylinder engine then you will only have two 02 sensors 1/1 is upstream and 1/2 is downstream. Upstream is the one closet to the engine and downstream is the one farther away from the engine.

If you have a six OR eight cylinder engine you will have four 02 Sensors. 1/1 means Bank One Sensor One. 1/1 and Bank one means right bank and right bank means the side with the number 1 spark plug. SO, 1/1 means, "Right Bank" Upstream 02 sensor. 1/2 means, "Right Bank" Downstream 02 sensor.

2/1 means, "Left Bank" Upstream 02 sensor and 2/2 means, "Left Bank" Downstream 02 sensor. Hope this helps and please visit my auto-repair-website at: http://www.bigasautorepair.com/

read your other ANON post first.
Double posted, an again , no engine stated.
is this the I-6, inline SIX? 2.5L

my wild guess is you get DTCs for bank 2, right?

example this? (this is farthest from crank pulley)
Trouble Code: P0050 2.5L I6
HO2S Heater Control Circuit Bank 2 Sensor 1
Number of Trips to Set Code: 2
Trouble Code Conditions:
HO2S-1 heater (bank 2) control circuit is open circuit.

standing in front of the vehicle looking at the engine bank 1 sensor 2 is the sensor after the cat converter on the bank on your left
bank one is the left cat ---bank 2 is the right cat. Sensor 1 is the one before the cat and sensor 2 is the one after the cat on either side

Ravi, I also have the same issue and confused between upstream left and right location.


I have problem with bank 2 sensor 1 and want to purchase a part. There are two part numbers 234-9007 for upstream left and 234-9009 for right.

So not sure the one on radiator (bank 2 sensor 1) side is upstream left or upstream right.

If you already know can you please reply?

did you have a cam sensor stored?? and also which bank sensor did you replace?? bank 1 and bank 2 can be easily mixed up. well not mixed up, but bank 1 is by the firewall. bank 2 is at the radiator. you may have replaced bank 1 instead of bank 2. so when you remove the air box to replace sensors and you are lookin at the connectors, bank 1 is the one on the right side head. bank 2 is the left side head if you are looking at it from air box side. if you are looking at it from crank pulley side, bank 1 is on the left and bank 2 is on the right head. what code do you still have stored??

Hello! Bank 1=Left bank...Bank 2=Right bank...Looking from the transmission side..towards the drive belt side...Left bank=left...right bank=right...Sensor #2 is located behind the cat...

Guru.....................Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

okay to make it simole for you......bank 1 is the bank where number 1 cyl. is located,so in your case you need to go to opposite side of number 1 cyl that being bank 2,sensor one will be the first on in the exhaust stream,if you need more let me know. have a good day

Oxygen sensors are numbered by which bank of cylinders they serve. Bank 1 is the left or drivers side bank of cylinders on the 4.3L which has the odd numbered cylinders 1,3, and 5. Bank 2 is the right or passenger side bank of cylinders numbered 2, 4, and 6. The Bank 1 Sensor 1 would be the sensor for the left hand side of the engine AHEAD of the converter. Bank 1 Sensor 2 is the sensor for the left hand side bank of cylinders BEHIND the converter.

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.

Most GM engines have #1 cylinder located on the left bank, (or Driver's Side) of the engine,

So, the answer to your question would be that you are looking for the sensor located before the catalytic converter on the right (or Passenger Side) of the truck.