imAC

I have looked everywhere online, but I keep finding different answers ! Is the Bank 1 Sensor 1 o2 sensor the one between the radiator and front of the engine ? or the one between the firewall and back of engine ? I need to get it fixed within 4 hours I just hope you all can help, thanks !

tomf

See this link for a link to a PDF file showing the location of the sensors you are interested in.

https://www.clublexus.com/forums/es3...xus-es300.html

Bank 1 sensor 1 also called the upstream sensor is the one between the engine and firewall. Bank 1 sensor 2 also called the downstream sensor is on the exhaust under the driver's seat. Bank 2 Sensor 1 is the one that is easily to see when you look at the engine from the front. It is in front of the engine.

Updated. When using "front" in the above context I mean toward the front of the car. The front of the engine is actually on the passenger's side of the engine compartment and the rear of the engine is on the driver's side. The engine is mounted sideways, if you will, in the engine compartment. So bank 1 is the right side (toward the back of the car) of the engine and bank 2 refers to the left side (toward the front of the car) of the engine.

2nd update: Quoting from the repair manual:

Bank 1 refers to the bank that includes cylinder No.1.

Bank 2 refers to the bank that does not include cylinder No.1.

Sensor 1 refers to the sensor closer to the engine body.

Sensor 2 refers to the sensor farther away from the engine body.

MikeLex

Bank 1 Sensor 1 is the one near the firewall.