where is the 02 sensor located, bank 1

 

Well... Lets start with what you are driving... Then, which sensor are you talking about? Depending on what you are driving, there could be up to three Bank 1 sensors.

For the 98+:

For the mid-02+, the post-cat sensor listed in the image above as B1S3 is called B1S2.

For the 96-97:


For '95 w/ OBD2 and I believe OBD1.5 PCM:

If you have a '95 with the OBD1 ECU, you will only have the upstream sensor (the one before the catalytic converter).

 

Sorry, I am driving a 95 Blazer 4X4 4 door v6 vortex. The code came up 131 and said to replace bank 1 sensor 1, but can't find it.

 

As the third picture Kyle posted shows, that would be the sensor before the catalytic converter.

 

thanks for the help, you guys are great! got it changed.