multiple misfire code

Yes, it can. But your truck need may just a tune-up. The error code from the O2 sensor is probably making the 'stumble' more pronounced. Wires, plugs, dist. cap and rotor should cure the 'cold stumble', especially if everything has more than 30k miles on it. You'll have to replace that O2 sensor if it's bad, but the cold stumble may not go away without the tune-up.

Thx, it has new plugs, wires, cap and rotor withing the last 30k. I will replace that 02 sensor and see how it behaves.

Bank 1 sensor 2 is the POST catalytic sensor on the driver's side. It has little to do with the air/fuel mixture; it just monitors catalyst efficiency. I have never heard of a bad post-cat sensor causing driveability problems. PRE catalytic sensor problems can cause driveability issues, POST cat sensors rarely do.

I doubt replacing the sensor will fix your problem.

Doc

Doc, I only have one cat. There are two pre-cat sensors on each down pipe though. I assumed that Bank 1 Sensor 2 was the lower one on the passenger side pre cat. Is this correct?

You're telling me that you have (2) oxygen sensors on each downpipe, for a total of (4) pre-cat oxygen sensors?

Doc

Bank 1 Sensor 2 will be the closest to the cat on the engine side of the cat. It's the same part number as the sensor between the cat and muffler(Bank 1 Sensor 3)

Yes, there are two sensors on each side of the Y pipe before the cat.

Do you have that p/n?

part number is 25312201 for Bank 1 Sensor 2 or Bank 1 Sensor 3, but replacing it probably won't change how the vehicle runs. Bank 1 Sensor 1 and Bank 2 Sensor 1 affect the air/fuel mix and Bank 1 Sensor 2's average voltage is compared to the average voltage of Bank 1 Sensor 3 for monitoring catalyst efficiency.

On engines with dual cats things work a little different, no Bank 1 Sensor

1. Bank 1 Sensor 2 post cat sensor for driver's side exhaust Bank 2 Sensor 2 post cat sensor for passenger's side Catalyst efficiency is determined by lack of "switching" of the post cat sensor over a determined voltage level

In that case the advice you've already recieved from Jeremy was correct. I just assumed you had a dual cat setup................my bad. Should have read your post a bit better!

Doc

No Doc..... it's not your bad...... he just doesn't know what he has. There aren't any Chevy trucks out there with the setup he describes. Why would there be? Bob

Bob....you are right. I made a mistake. I took a third look and found only one sensor on the driver's side and two on the passenger side. I apologize to all. I replaced the "upper" sensor, above the cat and I am still getting the MIL. I will pull the code again to see if it is the same one. As I understand it......Bank 1 is the "manifold" set and Bank 2 is the cat set of sensors. So Bank 1 Sensor 2 should be the "upper" one, near the cat, on the passenger side cuz there is no sensor that could be called Bank 2 Sensor 2 in a Y pipe configuration. I am assuming the after cat sensor is Bank 3. Mike

Incorrect: Bank one is the engine bank that contains cylinder # one, bank two is the engine bank opposite cylinder # one. The O2 sensors are then numbered sequentially down the exhaust system. Bank one sensor one is in the drivers side manifold. Bank two sensor one is in the passengers side manifold. Bank one sensor two is after the "Y" ahead of the cat-con. Bank one sensor three is after the cat-con.

IIRC, you are after a P0300 multiple miss-fire code, why you're dumping in O2 sensors for a miss-fire code is beyond me...

Thanx, I deserve to have to buy an "extra" one for listening to the Auto Zone idiots. I replaced the wrong one. I'm glad they are easy to replace.

My orig post had O2 codes in it also.

I found pn GM 25160540. The pic for this one looks right. The pic for your number does not look like the right connector.