O2s - Need Clarification

[Wess]

This may be a dumb question, but how many O2 sensors do we have on the V8? Is it three or four? Also, which one is which? Right now I have a P1131 which indicates HO2S-11 is reading lean. From what I understand this sensor is located pre-catalyst on the bank 1 (firewall side) of the motor. What are the other sensors called and what are their locations Thanks for helping a cornfused SHO driver!

 

[projectSHO89]

Four. Two on each bank, one before and one after each cat.

Firewall side is bank 1, radiator side is bank 2

Upstream (closest to engine, before cat) is #1 sensor, after (downstream) sensor is #2.

O2 sensors are designated as HO2S-(BANK)(UP/DN). Therefore, H02S-11 is bank 1, upstream sensor.

Steve

 

[Wess]

Thank you very much, that was most helpful!