Oxygen sensor confusion

Hi Amanda , I want to help you with your question, but I need more information from you. Can you please add details in the comment box?
USA car or NOT? USA is WJ jeep gas engines.
sensor B2S1 is bad. or worse.
or wires to it burned up , clamps bad and wires hit red hot
exhaust pipe
no engine told 4.0L i6 or 4.7L v8
must be v8. bank 2.

the front sensor is bad (aka upstream)
bank 2 is not cylinder 1 bank.
on USA car , bank2, seated in driver side
is right bank of engine is 2.
facing said engine is left bank.2.
the sensor is here

in the USA there are 2 v8 smog parts, CALF or FED

seen here clearly in the service manual oem I have in hand



the 4.0 liter is very trick this year,
it has an odd splite exh manifold
but only seen on calif engines,
see next photo for 4.0L engine,

The upstream on bank 2, which is the opposite of bank 1. Bank 1 is the side with the number 1 cylinder. Downstream oxygen sensors (after the cat converter) are always sensor 2, as in Bank 2, sensor 2.

Bank 1 is located towards the driver's side. Sensor 1 is located upstream just below the exhaust manifold.
EOBD II Error Code: P0134
Description:
Oxygen Sensor (O2S) 1, Bank 1/Heated Oxygen Sensor (HO2S) 1, Bank 1 - No Activity Detected
Possible Causes:
- Wiring.
- Signal wire between the Heated Oxygen sensor and ECM is disconnected.
- Heated Oxygen Sensor defective.
- ECM.

The 1999 5.3 V8 engine had 4 oxygen sensors. There are two catalytic converters on this engine, one on the driver side of the engine, and one on the passenger side of the engine. This is important to know, as the number of oxygen sensors is directly related to the number of catalytic converters on the vehicle. Driver side is referred to as Bank 1, passenger side is referred to as Bank 2. This is very important to know when looking up replacement oxygen sensors. There is one oxygen sensor in front of, or before the catalytic converter, usually referred to as a pre-catalyst O2 sensor. There is also one behind, or after the catalytic converter, usually referred to as a post-catalyst oxygen sensor. So, you have two oxygen sensors on Bank 1, and two oxygen sensors on Bank 2, for a grand total of 4 oxygen sensors.

Here is the low-down on oxygen sensors, and their location designations explained:

Oxygen sensors are screwed into the exhaust system at various points. Some people say that there are 4 oxygen sensors, but technically, that is not correct. Only the front 2 are considered oxygen sensors.

These oxygen sensors are screwed into the exhaust pipe or directly into the exhaust manifold, one on each bank. Because they are in front of the catalytic converter, this is often referred to as 'upstream'.

The other 2 are actually called catalyst monitors. They are oxygen sensors, but they serve a different purpose. They monitor the activities of the catalytic converters, thus the name, catalyst monitors. They are screwed into the exhaust one on each bank, after, or downstream, of the catalytic converters.

On a 4 cyl engine, there are only a total of two such sensors, the one in front of the catalytic converter is the O2 sensor, the one behind the cat is the catalyst monitor.

The location names for them are as follows:

• On a 4 cyl, the front / upstream is called "bank 1 sensor 1" and the rear / downstream sensor is called "bank 1, sensor 2."
  
  
• On a V6 or V8 engine:
  
  
  • the passenger side bank on a forward facing engine, or the bank closest to the firewall on a transverse mounted engine, is bank number 1, so the forward / upstream sensor on that bank would be "bank 1, sensor 1."
    
    
  • The driver's side bank (forward facing mount engine), or front bank (transverse engine) would be bank number 2, thus the forward / upstream sensor on that bank would be "bank 2, sensor 1," and the rearmost / downstream sensor on that bank would be "bank 2, sensor 2."

If there was a trouble code, the code should tell you which one? bank 1 or bank 2, and or sensor 1 or sensor 2. Bank 1 on a v engine is the bank with number one cylinder. Bank 2 is the other bank. Some sensors are labeled upstream and downstream in relation to the cat, before or after. Upstream is senor 1 and downstream from the cat is sensor 2.
Is it clear as mud?

On all cars, the bank 1 is where the first piston is...Your firing order on that car which is the first piston...Buy a chilton or a repair manual for your car and it will tell you which firing order your motor has....Its usually on the right hand side...Passenger side...Rule of thumb if you look at the spark plugs the one closest too you is usually the first piston....Bank 1 is located on the same side as the first piston...I hope this helps...

Bank 1 is always on the same side as the number 1 cylinder. Bank 2 is the other side of the engine. Sensor 1 is always before the catalytic converter. Sensor 2 is always after the catalytic converter.

Bank 1 sensor 1 is on the passenger side before the catalytic converter.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

bank 1 always refers to the bank that the No.1 cylinder is located and bank 2 is the other bank. Senspr 1 refers to the upstream oxygen sensor ( before the catalytic converter) sensor 2 refers to the downstream o2 sensor(after the cat) So if your No.1 cylinder is on the left side(drivers side) then your assumption is correct.

Sensor #1 is the sensor before the converter (upstream sensor)