I have a 2000 pathfinder with a 3.3. The computer says I have a bad sensor on bank 1 sensor 2. What side is bank 1 on?

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Question moved to model category.

Your friend is correct, 2 banks, 2 cats, 4 sensors.

https://www.nissanhelp.com/diy/pathfinder/projects/images/2005-2011-nissan-pathfinder-o2-sensor-location-01.jpg

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The easiest way to tell which is bank one and which is bank 2 is stand to the side of the engine and look directly across the front. one of the cylinder heads will be slightly more to the front than the other as the cylinders are offset. the leading head is where cylinder no 1 in located and that is bank one, the trailing head will be bank 2. Sensor number 2 will be the one located by the catalytic converter. Sensor no 1 is the one in the exhaust manifold close to the engine and no 2 is downstream towards the cat.

Here's your firing order cylinder one is bank one,sensor two is at the catalaytic convertor on that side,which is the passenger side,the oxygen sensor.

bank 1 is the side cylinder #1 is on and sensor 2 is the second sensor in the exhaust for that side.if this has only 3 sensors one on bank 1 and one on bank 2 then it will be the sensor behind the cat.if it has 4 sensors then it will be on the same side as bank 1 but behind the cat for that side bank 1 as it will have 2 cats.

The bank refers to the side of the engine. Bank one is always the same side of the engine as the number one cylinder. Bank 2 is alwasy the other side of the engine.

Sensor refers to before the cat or after the cat. Sensor 1 is before the cat and sensor two is after the cat.


So Bank 2 Sensor 2 is on the engine opposite of the number 1 cylinder and after the catalytic converter.

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

near the exhaust manifolds, in the exhaust pipes,on both sides.

Bank one is on the side of cylinder one. Cylinder one is typically on the driver side. Although, you have to be careful here. Just because the code mentioned the O2 sensor doesn't mean the sensor is bad. For instance, a code of P0171: sensor indicates lean, bank one sensor; one is not a bad sensor. That is a good sensor telling you that the engine is running lean on bank one. If you get a different code, then it could the be the sensor.

ON THE EXAHST

Your auto has four O2 sensors. Two upstream and two downstream; With two banks. Bank 1, sensor 1...and bank 2, sensor 1 are the two upstream (exhaust manifold before the catalytic). Bank 1, sensor 2 and bank 2, sensor 2 (other side of catalytic)

Code 1131= upstream; bank 1..sensor 1
Code 1151= upstream; bank 2..sensor 1
Code P0136 (generic code) bank 1..sensor 2 (questionable)

I wouldn't spend the money to purchase 3 sensors. Highly unlikely all three are bad; Cost is about $40/ ea.
Since there isn't a code for the cat's themselves, I would suspect the O2 circuit is malfunctioning. The rough idle is another clue.


Take an ohmmeter set it on X10 scale and measure the resistance from engine to body and body to negative post on battery terminal. You should read zero ohms (full needle deflection). If you do go buy two upstream O2 sensors. If you read
open or a high resistance run two straps from eng. to body...and body to neg.batt. post.

FixYaWIZ................saailer



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

Bank 1 is the drivers side. But the sensor you want is the one farthest back, right before the muffler.