Hi everyone. New here i just got a 98 4runner but im having some trouble and was hoping for some help.
I live in cali and need to get it smogged but ive failed once and i have a cel p0133 i believe its the o2 sensor for Bank 1 sensor 1. Problem is i talked to a mechanic and he says theres 4 o2 sensors, 2 on the engine denoted by bank 1 and 2 on the exhust denoted by bank 2. All ive been able to find are the two before and after the cat. If some one can help me understand where to find sensor 1 bank 1 it would help alot.

here are smog numbers

hc
max 51 (35)
mea 16 (15)

co
max .65 (0)
mea .79 (0)

no
max 512 (765)
mea 644 (524)

parenthesis = 25mph

so along with that, im hoping the o2 sensor will correct the no measure.

THANKS

 

There are only two O2 sensors, one before & one after the cat, just like you found. Bank 1 is the right side (passenger) of the engine & Bank 2 is the left side (driver). Your exhaust is routed down the right side of the vehicle so the sensors are Bank 1, sensor 1 & Bank 1, sensor 2.