How many Oxygen Sensors?

[Kukailimoku]

So, do I have two, three, or four Oxygen sensors?

2005 Dodge Ram 1500 SLT 4WD Quad Cab 5.7 Hemi gasoline.

In previous years I have changed two - one upstream ("before" the catalytic converter) and one "down". i THOUGHT that were all. But internet searches elsewhere than this forum hint at possibly having several O2 sensors, with each sensor particular to only one "bank". But I can't get any specific info on whether my truck has O2 sensors for each bank or just the general up/down stream two. I've never heard of O2 sensors being specific to one bank, is this a real thing?

How would I know? (Obviously I could crawl under/around/through the underside and trace every possible exhaust path, but even if I did that I might still miss seeing it on the other side of the pipe) and I was hoping people definitively knew and could tell me whether I have two, three, or four. Before me having to trace exhausts to see how many I have.

???

 

[Fitz-0518]

My 03 5.7 only has two. Up strem and down stream. I believe you can use one of the discount dealer sights or possibly the MOPAR parts sight. Use the search engine to locate the diagram that shows the sensor location. Or just google locate 02 sensors 05 Ram 5.7

 

[Kukailimoku]

Okay, I do have four.

I'm an idiot; years ago when I had changed two O2 sensors I THOUGHT that I was looking at the only exhaust path. Because I have only one tail pipe, and I found one exhaust path with the cat and an O2 on each side of it, I thought I was done. Well, today I finally crawl around and lo and behold there are TWO exhaust paths coming back one from each bank, and they merge together somewhere at the 1/3 or half-way point along the length of the truck and terminate in that one tail pipe. So in the past I was only checking the exhaust on the passenger side. I realize now that there is a ditto path on the driver's side; cat, two O2 sensors. Mystery solved. I had thought that both banks had already merged somewhere up/forward where I couldn't see. Who'da thunk that two separate exhaust paths could go so far back and yet NOT end in two tail pipes, merging so late along the path?

 

[HemiLonestar]

03 is the only year with a single up and down stream (single cat). Starting 04 dual cats.

 

[chrisp2493]

Yep what he said ^ 2003 has one cat, 1 upstream and 1 downstream. 2004 on up have a cat on each side of the engine and 2 sensors for each cat. Bank 1 is the driver side, bank 2 is the passenger side. Sensor 1 is upstream, sensor 2 is downstream. So if you are trouble shooting from a code, o2 sensor 2/1 would be passenger side upstream. 1/2 would be driver side downstream.


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