How to replace the Oxygen Sensor?

Hello, Bank 1 is the passenger side of the engine, so facing the front of the engine it will be the bank of cylinders to your left, they are 1, 2, 3 on the passenger side. That side of the engine can be a little tight, the front Oxygen sensor will be in the exhaust coming that passenger side exhaust manifold. Is the PCM setting a code for the B1S1 oxygen sensor? And is it a slow response code or a heater circuit code?

Most new oxygen sensors come with a little bit of anti-seize on the threads, and you will need an oxygen sensor socket, it makes things much easier, you can get one at any auto parts store. But if you are getting a code for the Oxygen sensor heater circuit, you would want to test it to make sure the sensor is getting power and being controlled by the PCM on the ground side of the heater circuit. You can also take a resistance measurement to make sure the heater inside the sensor is open circuit, verifying the sensor does need to be replaced.

https://www.2carpros.com/articles/how-to-replace-an-oxygen-sensor

If you follow the exhaust manifold down the exhaust pipe on the passenger side of the engine, you will see the front Bank 1 Sensor 1 Oxygen sensor threaded into the exhaust pipe. It will have a 4-wire connector to it. I'll try to find a picture if you are unfamiliar with oxygen sensors.
There will be 2 wires of the 4 that are the same color, those are the heater wires for the sensor. The heater gets the sensor up to operating temperature, without it the sensor will not start to respond to the exhaust gases, hence the reason for mentioning it. The front Oxygen sensor should have a voltage fluctuation of 0.1volts to 0.9 volts roughly.
This waveform below is an example of a regular front oxygen sensor voltage. The first half is normal sensor operation, the 2nd half is a slow responding sensor, in some cases if the sensor gets stuck low (so around 0.1volts, below 0.450volts) the engine computer will set a lean exhaust code. If it gets stuck high (0.9volts, above 0.450volts) the computer will set a rich code.
This is important to know, because areas with a bad gasket such as a bad exhaust manifold gasket can allow air to enter the exhaust before the sensor, and this will cause the oxygen sensor to read a lean condition or respond slow, depending on how bad the air leak is. Additional air leaks (vacuum leaks) affecting Bank 1 side of the engine can also cause this situation. But first find the sensor, check the wiring, make sure it's not broken anywhere and the connector is ok, since these sensors are in the exhaust pipe and under the truck, they are exposed to the elements and a rough environment. Let us know if you need any more help with anything at all.

This picture should help you find it.