I got the truck started and it stayed running. I connected the OBDII UP WHILE IT WAS RUNNING. I got P1391. Needs the crankshaft sensor as I predicted. It also said that the first 02 mon inc and the second O2 was okay. And then the catalyst mon inc. How do I know which oxygen sensor I need for the truck. Please help. I have to tell you that I’m a little excited that I know what’s wrong now. Yeepee

 

It's Alive! WooHoo!
You want NGK or NTK as it will probably say on the box. Its the same brand. Stay away from Bosch. NAPA auto parts carries them.

 

Okay question. On my scanner, the first O2 sensor that was in the list of everything, is the one that had the inc following O2 mon. Does that mean that it’s the upstream sensor 1. This is all new to me. I’ve never gone so in-depth working on any of my vehicles in the past as I have with this dakota

 

If you imagine the stream starts at the exhaust manifold the one before the CAT will be the upstream sensor. IDK if there is a difference in the sensors on the vehicles with upstream and downstream sensors I only have the one before the CAT on mine. I never thought about it. The parts guy should be able to tell you or searching through Rock Auto and comparing the part numbers should tell you if they are the same or different.
Here ya go. It looks like RA does list and upstream and downstream part. Denso is also a good part brand for the Dak. https://www.rockauto.com/en/catalog/...2)+sensor,5132

 

Bank X sensor 1 is the upstream, Bank X sensor 2 is post-cat.

 

I'm baffled by the "first 02 mon inc"?? does that mean its OK or bad or?

 

I know nothing about upstream or downstream when it come to this. I only know about upstream and downstream when I’m fishing. LOL....All I know is the first O2 listed on my scanner is the one that’s bad.
I have to say that I’ve learned a tremendous amount of knowledge regarding this truck over the last two or three weeks. It’s insane. Why can’t they just make them like they did back in the day. Back in the 60’s, 70’s, and 80’s

 

yea this page is a great resource. Some quality people and info on here.

 

That means the O2 monitor is incomplete. The PCM pays attention to them, and that's how it usually figures out one is bad. Trouble is, they go bad slowly, and the PCM doesn't figure it out.......

 

Well, it's the same thing; think of your exhaust pipe as a creek, and the cat as where you're standing. So, one way is upstream, and one way is downstream; towards the motor is upstream, towards the tailpipe is downstream.

Go ask the tree huggers; but then again, air IS cleaner than in the 60's and 70's; vehicles are safer for the occupants; and gas mileage hasn't been hurt much if any with the increasing weight and horse power.

RwP