Which cylinder is number 1

The firing order should be 1 2 3 4 5 6
Your cylinder banks are odd and even numbered.
Looking under the hood, front bank of cylinders , from left to right, 2 4 6
The rear bank of cylinders, left to right, 1 3 5

bank 1 refers to the side of the engine. on a four cylinder there will onlyu be a bank one. a v-6 will have a bank 1 and a bank 2. Bank 1 will be on the same side of the engine as cylinder number one. Bank 2 will be the opposite side. Sensor 1 is always before the catalytic converter. Sensor 2 is always after the catalytic converter.

So , for example, if your looking for Bank1 Sensor2 it will be in the exhaust pipe after the cat on the same side as the number one cylinder.

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

bank #1 is the driver side or left side which include cyl 1,3,5,7 and bank #2 is right hand side and cyl 2,4,6,8 are in bank #2. ciylinder #1 is left hand side of engine and is the first cylinder from the front of engine.

Firing Order 1-3-7-2-6-5-4-8 Bank 1 on the right Bank 2 on the left Cylinder #1 on the right Cylinder #8 on the left last one ,which is the driver side

Since you don't say if you have 4 or a 6 cyl, I will give you both.On a 4 cyl count from the front of the engine. The belt pulley is the front.On a 6 cylinder, one bank of cylinders is more forward that the other. On the forward bank the the front cylinder is number 1, so the front cylinder on the other bank is number 2. So number 3 is next to number 1. The second cylinder on the forward bank.

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.

Bank 1 is normally left but the correct way to find where bank 1 is find cylinder number 1. Bank 1 will always be where cyl 1 is.

Sensor 1 = front, pre cat

Sensor 2 = rear, post cat

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.

2000 4.0 jaguar s type cylinder firing diagram:
FRONT OF CAR
5 1
6 2
7 3
8 4