Where the transmission filter on a 2006 Nissan action

https://www.autozone.com/repairinfo/specifications/specificationsMain.jsp?childCatName=Transmission+Fluid+Type/Capacity&childCatId=28100280&categoryNValue=28199999&categoryNameForTitle=Fluid+and+Chemicals&categoryName=FLUID+AND+CHEMICALS&childCategoryNameForTitle=Transmission+Fluid+Type/Capacity

I don't know about Nissan but my 2006 Ford Freestyle AWD CVT transmission was a high pressure sealed system requiring a special pumping machine to change the fluid. It didn't even have a dip stick. Does yours have a dip stick? If not, I suspect that you'll be in a similar boat. My Ford had to have the engine and transmission partly removed from the car to replace the high pressure fluid filter. Cost? $500.00 U.S. at the Ford dealer. No other shop would touch it. Good luck.

hi sherman.
go to this link and see if it helps you find out.
Does 2006 Nissan Frontier have 6 speed transmission Google Search

It could be any of a few things but a semi-blocked exhaust or cat is somthing that fits your description very well.

51 and 1168 are O2 sensors. Check for vacuum leaks and make sure the hoses are hooked and tight from the air filter box to the throttle body. P0725 is engine speed sensor/ input shaft speed sensor on the transmission.

you possible could get some action as the service was not done properly
if there is no problem with the transmission performance
may be an oil change and filter clean will show any problems
to do the filter the pan has to come off and if there is a problem mechanically there will be metal flakes in the pan
if nissan knows of transmission issues then those issues can still be covered by warranty even after the period ends
You will have to get clear legal ,advice for that
at this point , I would take it to an accredited professional transmission shop and ask for an transmission oil change, filter clean , clutch pack and band adjustment and a report on any problems seen during the service
I would not be considering a replacement box yet as it may not be necessary

automatic or, standard transmission?
automatic: transmission replace your transmission oil filter
standard: replace your clutch

No, there is a drain plug on the bottom of the drain pan, but you will have to take the pan down to replace the filter. Go here for step by step instructions.

Mazie, Slater, Katz & Freeman, LLC is putting together a class action lawsuit against Nissan Motor Company related to issues where a leak from the radiator into the transmission is causing radiator and transmission failure. This problem is prevalent on several 2005, 2006 Nissan Frontier, Xterra, Pathfinder models. My vehicle is a 2006 Nissan Frontier. Please share your information so Nissan will have to accept responsibility for their defect. Go to www.transmission-lawsuit.com to share your details.

Check the fluid level of the transmission. Also if you haven't done so in the last 30k miles change the transmission filter/fluid and pan gasket.