02 Sensors, Why so many?

[mediumrareintexas]

My 02 camaro has 4 02 sensors. One before each cat and one after each cat. Why so many? Also, I just installed my WB 02 before the cat on the passenger side. To get a true 02 reading, logically, it would seem that you would need to install it after both 02's at some common point. Does that make sense? ???

[03_Z06_Blue]

The front set of O2 sensors (before the cats) monitor the air to fuel ratio (AFR) of the engine during closed loop operation. The left front O2 monitors the left 4 cylinders, and the right monitors the right cylinders. Each sensor reports the AFR to the VCM (computer) so that it can maintain a proper and efficient mixture (14.7 parts air by weight to 1 part of fuel). Previous car models did this with one O2 sensor (after the Y pipe junction) to do the same thing. A sensor on each engine bank does a better job, as in your car.

The second sensor on each side reports if its cat is effectively neutralizing unburned fuel, which it is supposed to do. If not, the VCM stores the defect and puts on the "service engine light." The purpose of the second set of sensors is to make sure that the car does not excessively pollute the air.

The newer cars (1996 and up) have a much more complex computer system than the older models, and a lot more sensors to keep things running well.

Hope this helps,
Paul

[mediumrareintexas]

Great explanation Paul. Much appreciated. So when the PCM reports a DTC indicating a too lean condition, bank one sensor one, does that indicate a problem with the AFR on the left 4 clyinders or just a too lean condition overall? ???

[horist]

just bank 1 so just those 4 cylinders..

[mediumrareintexas]

Thanks for your reply. This forum is really helpful. So why would only one side be lean? I've been getting this DTC since I installed the procharger. The injectors are all the same, or I should say, they all came in the same unopened box. 42 lb SVO. So I'm thinking maybe the 02 sensor on the left side may be a little more sensitive than the sensor on the right side? ???

[horist]

Thanks for your reply. This forum is really helpful. So why would only one side be lean? I've been getting this DTC since I installed the procharger. The injectors are all the same, or I should say, they all came in the same unopened box. 42 lb SVO. So I'm thinking maybe the 02 sensor on the left side may be a little more sensitive than the sensor on the right side? ???

1 side can be lean if an injector is failing, if there's a header leak, maybe obstruction in intake manifold?

Anything that causes too much air in a cylinder or not enough fuel basically... and header leaks (which would yield a false lean condition)

It's normal for each side to be slightly different... but if 1 side shows really lean and other is normal... i'd look at an injector clog or header leak/exhaust leak of some sort