Any info on what this is??

 

Passenger side rear O2 sensor. Just for fun, check to see if your air filter is dirty.

 

And if it is, do i need to get a new one or just just clean it and get the code cleared? And would I notice anything if the O2 sensor has failed?

 

With the mileage you have on your truck, you would need to replace all 4 of the 02 sensors cause by mileage they are all about to wear out. What octane gas have you been running?
To answer your othe question, you can't clean an 02 sensor and gain any benefit from it.
Also Atlantic British has a sale on 02's for your D2 for $59 a piece.

 

I have been putting premium in for about a month, i wasn't aware that it need it until a opened my eyes and say that it said it on the gas cap door. But I can tell a HUGE difference now that I switched. So basically it sounds like I need to replace all of them. How long do they generally last, just out of curiosity? I will look into getting 4 new ones soon. THANKS!

 

They are usually good for 100,000 or so if they don't get contaminated.
The sale at Atlantic British last till the 23rd of this month. If you go past that try Auto Zone, the usually have some pretty good prices.
When you are done then ask Auto Zone to clear your codes.

 

oh yeah, i meant to ask. Are they easy to replace myself? Or is it something my indy mech. needs to do? Thanks for the quick responses!

 

If you have the right wrench, you can do it easily. Soak them in penetrating oil and it will be a whole lot easier.

Always alwaya always run premium. I would run a can of BG44 injector cleaner through it too.