I know I need new ones but how many do I need ? Does it make a difference on the brand ? I want to cheapest, I was looking on Ebay but I'm not too sure what to get and how many ?

It's a 2001 Dodge Laramie SLT, 4 door.

He sucks back the fuel, it's crazy (yes, his name is Jake).

 

California Emmisions uses 4, Federal Emmisions set up uses 2. Open hood look on sticker or get under and look. Don't go cheap or you will be sorry. Go to rockauto.com and get the NTK sensors. And while your here on DF, do a search for Plenum.

 

And only replace the upstream sensors..... downstream only monitor cat efficiency. If you aren't getting a code for them, leave 'em in there.

 

What are you looking for on the sticker to determine weather or not you have a Cali truck. From what I can gather my truck was either sold in San Diego or LA but looking at teh under side of my truck I only see two.

 

right after the Y there should be a third... it's curiously unmonitored.. your pre-cats are monitored upwind and downwind for a total of four o2's though..

 

The sticker says blah blah blah, if Federal. If it is California it will say so. Maybe some one with a Cali emission will chime in.

 

the sticker is sometimes on the hood itself, and its sometimes adjacent to your little 'belt routing' diagram..

You don't need to look for it though- it will be just as quick to look at either exhaust manifold and follow it to the pre-cats.. If there ARE pre-cats, that's going to be your first clue.. Cali has a pre-cat just above the collector on each side.. they have an o2 sensor bung welded into the pre-cat itself, and an o2 sensor within a few inches aft of the pre-cat.. all four sensors are visible from the engine compartment..



this image is the drivers side manifold of a cali emission 5.9L magnum v8.. the pre-cat is a little north of dead center in the pic.. The pipe from the back cylinder is blocking the view of the upwind o2 sensor..



this is a pic from the ground, looking up at the drivers side pre-cat.. both o2 sensors are visible.. the one up top is new..

IF- you do have Cali emissions, you're going to need a cali specific o2..

If you purchase NTK, which is the rec'd brand here and elsewhere- you're going to want the ones with product code ending in 135.. NOT 139, but 135...

There is no reason to waste money on replacing the downwind o2's, they just tattle on you.. If they aren't tattling now, they are still good.

Now IF- you have federal emissions, I have some brand spankin' new o2's (NTK ending in 139) I'll sell you.. I effed up and bought the wrong ones.. I have two, you'll need only one.. $20?

PM me if interested.