Hey All,

I'm getting some pretty darn bad MPG, so, I figured as part of my problem solving I'd replace the O2 sensors, being that I've read that could be a problem. I've a '99 5.9L, and from what I previously understood, I should have only two O2 sensors, one before the cat, and one after the cat.

I called NAPA, and they informed me I actually have two PRE cat, and one POST cat. I was a tad confused, but considering how long ago it was that I read the information, I just figured they were correct. I purchased them both, (NTK 23151 and NTK 23506). I was a tad skeptical, but it's bloody rainy out and I wasn't about to crawl underneath.

That was until I started reading the manual, and I read a part that said after '98, there were only two O2 sensors. Bah. So I crawled underneath, got utterly soaked (I park outside) and see that there is indeed only two - one is pretty much right into the cat before it. So, being that NAPA is telling me there is three, and when I look up these NTK sensors online I get a Left and Right O2 sensor, does anyone have a part number? Or another brand I should be going with? It seems all the ones I attempt to look up online state there are two PRE cat, left and right. Yeah, long winded to get to the point, but I like telling stories

Thanks,
Chad.

 

I have a 98 1500 with a 5.9L and there's only 2 one pre-cat and one aft. The only thing I can tell you to do once the weather clears up is to either 1) check at both exhaust manifolds top and bottom and follow the pipes on both sides until they meet at the cat or go to the dealership and have one of the service guys show you were this "ghost" O2 is located.

 

dont know if this helps but i had some bad mpg too and i looked at my O2 senosrs, i also i have 1 before and 1 after the cat. i just cleaned mine though, they werent that bad

 

Had the same problem with the parts stores when i went to do mine. Had to get the parts guy to crawl under my truck and show him that he was wrong there is only on before the cat and one after. I dont know where they get this left and right from.Need less to say it was a bitch to get the one before the cat its like they couldnt find the part # after i took it out and gave to them all they could find was the one after the cat had to go to the dealer ship to get the one before the cat and even they where confused (DAM PARTS GUYS)

 

Joy. Guess I'll take these two back (Gotta love getting a discount at NAPA, so didn't pay too much) and see if anyone can track down the CORRECT number. It's still pissing up here, so I don't forsee going BACK under the truck to take the stock one out any time soon.

Chad.

 

[:-] What type of gas milage is normal for a dodge ram 1500 5.9

 

Well, I used to have around 13mpg, and now I'm getting about 9mpg, which well... I'd rather 13.

Chad.

 

I don't know just guessing.....But maybe they think it is 2 before the cat and it really is just saying to look at it and see if your sensor is on the left side or right side of the cat and get the 1 that is for your needs...Maybe their is a slight difference in the way it is mounted in the cat from one side to the next????

 

here is a good part# for the o2 sensor disregard the left and right garbage... Bosch part# 13100

 

Yeah, managed to sort it out. I didn't know about the Bosch one, so I grabbed the NGK/NTK one. The pre-cat number is 23151, and post-cat is 23099

Chad.