Ok, so I have owned my 2015 Ram for 2 days and ECT light comes on

[Tremper126]

I have had the SERVICE ELECTRIONIC THROTTLE CONTROL on going for about 9 months now. Originally would come on every few hundred kms and vanish when I shut the vehicle off. It has since become more consistent and I can not go more than 30km (if im lucky) on the highway without the SETC light coming on and losing power. Truck averages about 100 km/h on flat ground, but fluctuates about 20 km/h in either direction depending on the grade. Can usually drive city speeds for a long time without any issues. I have had it in to a local mechanic early into all of this and the code cleared before any repair was suggested. Now ive had a $550 diagnosis from the dealership to "replace exhaust temp sensor to start" and im not sure its worth following through. Truck showed codes "P0546" and "P2BA9"

I would buy the sensor and replace yourself. Makes sense why it averages around the same mileage before it throws the code

 

[ingenthronc]

I had/have the same problem. I purchased my truck and with in the first week I got the SETC & p0229 code after driving on the highway about an hour. Ive had it in the dealer twice for the issue with no luck so im going to see if i can fix it myself. I cleaned my MAP sensor and EGR tube, i did the new GDE tune, and ive been running hotshot in my fuel. now i just need to go on a long drive to see if it comes back on. It will only show after about an hour of non stop driving on the highway.

 

[CAVEMANN]

I have stage 1 Sofaking tuning in my rig and it's great, I don't know about fuel mileage yet but has definitely slowed down regens. OP, you mentioned Edge tuners in your original post, Edge doesn't make tuners for the ECO, but I highly recommend an EDGE CTS 2 or 3 with the tunes so you can monitor what's happening, after purchasing a CTS 3 I wish I had gone with a 2 because it supports forced regens, for some reason the 3 does not. The owners manual states to fill the DEF tank when doing an oil change, that's what I have been following & it takes afout 3 1/2 to 4 gallons.