O2 Sensor location wanted.

I have a 96 Jimmy SLT with code 140.

Code: 140 (No activity noted O2 sensor - Bank1 sensor 2)

Where is Bank 1 Sensor 2 located exactly. Diagrams?? Ive been searching the web for the exact location but cant find a defenite answer.

thanks.

What engine?

What engine?

Vortec 4.3 - I know theres 4 of em but cant pin point which one it is.

If you have four O2 sensors, bank 1 sensor 2 would be right before the cat.

If you have three O2 sensors (like the majority), bank 1 sensor 2 would be right after the cat.

If you have 4, bank 1, sensor 2 would be the bank where #1 cylinder is, AFTER the catalytic converter

If you have 4, bank 1, sensor 2 would be the bank where #1 cylinder is, AFTER the catalytic converterThat would be true on vehicles that came with dual exhaust, but he has a 1996 Jimmy, they came with single exhaust. The information that I provided is correct for his vehicle.

That would be true on vehicles that came with dual exhaust, but he has a 1996 Jimmy, they came with single exhaust. The information that I provided is correct for his vehicle.

I asked a GM tech and he told me that the O2 sensor is located the second sensor after the manifold; I think this is under the driver' seat by the transfer case - GM gurus please correct my if Im wrong but Im looking for a definite answer on location of the sensor.

Never seen the upstream sensor listed as #2...It's after the cat. It's also called the catalyst efficiency monitor..

Never seen the upstream sensor listed as #2...It's after the cat. It's also called the catalyst efficiency monitor..
Let me see if I can explain it better. Oxygen sensors have two main designations Bank 1 and Bank 2, this tells you where to look. Bank 1 is on the same side as cylinder 1. Bank 2 is on the same side as cylinder 2. On systems with a single outlet, the exhaust is refered to as bank 1 after they merge. On most models this is right after the Y pipe. The second part is the sensor number, this number corresponds to the position of the sensor. They are numbered in order starting from the engine. Bank 1 Sensor 1 is the first sensor closest to the engine on the side with cylinder 1 (driver side on GM). Bank 2 Sensor 1 is the first sensor closest to the engine on the side with cylinder 2. Being that these are the only sensors before the Y pipe, all other sensors will be called Bank 1. Bank 1 Sensor 2 will be the next sensor closest to the engine. On models with 3 oxygen sensors this will be the sensor AFTER the cat, and is the cat efficiency monitor. On models with 4 oxygen sensors this will be the one BEFORE the cat. On models with 4 oxygen sensors the one AFTER the cat is called Bank 1 Sensor 3, and is the cat efficiency monitor. I have yet to discover why or even find someone that knows why, but I know for a fact that some of the S/T vehicles came with 4 oxygen sensors, even though most came with 3 oxygen sensors.

All the above applies to the models with a single exhaust outlet.

Let me see if I can explain it better. Oxygen sensors have two main designations Bank 1 and Bank 2, this tells you where to look. Bank 1 is on the same side as cylinder 1. Bank 2 is on the same side as cylinder 2. On systems with a single outlet, the exhaust is refered to as bank 1 after they merge. On most models this is right after the Y pipe. The second part is the sensor number, this number corresponds to the position of the sensor. They are numbered in order starting from the engine. Bank 1 Sensor 1 is the first sensor closest to the engine on the side with cylinder 1 (driver side on GM). Bank 2 Sensor 1 is the first sensor closest to the engine on the side with cylinder 2. Being that these are the only sensors before the Y pipe, all other sensors will be called Bank 1. Bank 1 Sensor 2 will be the next sensor closest to the engine. On models with 3 oxygen sensors this will be the sensor AFTER the cat, and is the cat efficiency monitor. On models with 4 oxygen sensors this will be the one BEFORE the cat. On models with 4 oxygen sensors the one AFTER the cat is called Bank 1 Sensor 3, and is the cat efficiency monitor. I have yet to discover why or even find someone that knows why, but I know for a fact that some of the S/T vehicles came with 4 oxygen sensors, even though most came with 3 oxygen sensors.

All the above applies to the models with a single exhaust outlet.

Thankyou. This makes most sense to me right now. I will be checking it out tonight. :)