IS200 / 300 How many O2 sensors / CEL / P0155

[andykao]

I have an IS200 (1G-FE engine) but i believe this applies to the IS300 as well. I got a CEL, checked it with the tester and the error code is P0155 - Bank 2 Sensor 1 Malfunction (will replace it).

But then i wanted to check if the other sensors are working properly. Apparently i got this :
B1S1 - normal voltage
B2S1 (the damaged one) - lower voltage than expected
B1S2 - normal voltage
B2S2 - no reading, no voltage, no nothing.

Now i know that the first two sensors (Bank 1 Sensor 1 and Bank 2 Sensor 1) are the precat sensors and are responsible for the AFR.
The S2 sensor is after the cat and probably just checks if the cat is working properly or not.

Don't know where the S2 sensors are, are they after the precats or after the main cat? And are there 2 of them (after each precat) or just one (after the main cat)?
Don't know if i have one missing (B2S2), damaged / unplugged or the car has just 3 O2 sensors.

Any help would be appreciated.

[noby76]

from my memory on when i had my IS300 i believe there are 3 senors in total and not 4. that is 2 pre-cat sensors that is Bank 1 sensor 1 and Bank 2 sensor 1 and 1 post cat sensor which is just a rear sensor and it does not belong to any bank per say . i have attached an image from Denso to help you.

 

http://densoautoparts.com/Portals/DensoAutoParts/Resources/file/DENSO O2 Sensor troubleshooting tips.pdf