I have a 2000 Toyota Camry V6 with a California emissions package. I am getting a P0155 error on my OBD tool. This is either a O2 Heated Oxygen Sensor or An A/F sensor. I get confusing information when I look this up on line. I, so far, have NOT been able to find a picture of exactly where this sensor lives so I can test it. My Haynes Repair manual is at best, not helpful. It does not even mention bank 2 sensor 1.

Can someone point me to, or provide me with a picture of where this thing is? I've got a bad feeling it is way up under the car but it might be marked in the picture below.

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  • Welcome to Motor Vehicle Maintenance & Repair! Commented Mar 25, 2021 at 9:46

1 Answer 1


P0155 is stating the heater element in the O2 sensor at bank 2 sensor 1 is slow to heat up. This usually indicates the O2 sensor is going bad, but not entirely there yet.

To figure out which is bank 1 and bank 2, it is most often derived from the number 1 cylinder for the engine. And generically, the number 1 cylinder is most often the forward most cylinder of the engine when looking at the front of the engine (not the front of the vehicle). In the case of the Toyota V6, the number 1 cylinder is the front left, which means the left side is bank 1. Sensor 1 refers to the forward most (upstream) O2 sensor. Sensor 2 would be the post (after) cat sensor. In your case, the sensor you have circled is the one you're looking for.

  • @D.Scruggs - If this answers your question, please don't forget to use the check mark to select it as the answer, as well as up vote (if you feel so inclined). Thanks! Commented Mar 25, 2021 at 20:07
  • This was indeed the correct sensor. I replaced it with the correct one, eventually, and everything is fine. The important thing is to determine if you need a California sensor or a non-California sensor. Thanks to all of you.
    – D. Scruggs
    Commented Jul 16, 2021 at 21:28

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