Tjfaz

Hey guys just some confusion is which sensor is which. Bank 1 sensor 1, Bank 1 Sensor 2, and the third sensor. I found one on the front of the engine, and one behind the engine. Just not sure which is which. I have the V6 VVTi.

tomf

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 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.

Tjfaz

Thanks Tom very helpful!

tomf

Here is an engine diagram showing the location of two of the sensors in which you are interested.

Lexus 1997 engine diagram.pdf