How much would a bad O2 Sensor hurt MPG if it's the upstream sensor? And would it be worth it to change that before my plenum fix? Or will it simply ruin the new sensor?

And while I was looking them up, there were left side and right side sensors. WTF is up with that? I thought there were only 2.

Thanks!

 

Have a look under your truck, and see how many ya got. I think the california trucks had a handful of them under there......

O2 sensor is one of the biggest players in fuel economy. It has the most influence over what the PCM decides to do for fuel. A sensor that is slow/wrong/inaccurate, WILL have a negative effect on how your truck runs, and can seriously impact fuel economy.

You can try cleaning the one that is in there now, or, simply replace it, and do the plenum SOON.

 

All of our 2nd gens Rams (besides Cali) only have two O2 Sensors correct Hey_You? One before the cat and one after?

 

Okay, I'll probably just clean it off and see if it helps for now. I was hoping to get by another month before tearing the top end apart because of boating season.

 

My 97 only has one sensor. its pre-cat. same with the 94 i had. i believe the later models do have two. but just crawl under and check.

 

Well aren't you lucky. I tried cleaning mine in gasoline and/or brake cleaner.

 

Then the 2nd one, post-cat, was removed/relocated at some point. Almost 100% guarantee you that your truck came from the factory with two O2 sensors. Every Dodge Ram starting with model year 1996 did, as that was the switch to OBD II (and the beginning of the two sensor system).

As far as the pre-cat O2 sensor goes, I am with everyone else, pretty much. It has a very large effect on your power and MPGs.

 

Not tho throw a wrench into things, but my Cali Ram has only 2 sensors (thank God). Pre and post.

 

I am currently diagnosing a a rough idle problem on my 98 2nd gen and had my truck hooked up to a scan tool watching live data. There are most definitely two sensors on my truck B1 S1 ( the pre cat ) and B1 S2 ( post ). My 04 3rd gen has more than two but that might be a different thread LOL. Any way my pre cat was only switching between 80 and 200 mv giving me a lean condition which had to be affecting my MPG!! Now not to hijack his thread but since we both need new sensors how about some suggestions. Brand? Denso or NTK or Bosch or Walker and Best place to purchase??

 

As far as brand is concerned, I heard our trucks respond well to NGK'S. Ask around to be sure.