So my Range Rover dealership is telling me I need an auxiliary battery for my eco start/stop, my engine light is showing and they are trying to tell me it’s because of a “small battery”, now they said they replaced that a couple months back, but now there telling me the battery that they replaced was the primary battery, I just feel like there scamming me I just don’t know what to do anymore.

 

It is true about the small battery dedicated to the ECO start. It is under the cowl by the passenger wiper arm. I had mine replaced under factory warranty and it worked for a month. I never made it back to see if it is a programming issue or parts. No engine lights on then or now, but if I pushed the ECO button it said "ECO start/stop not available". The story the are telling you seems correct. But the little battery is a $300 dollar part from them, so make sure that it is worth the money to save a little fuel.

Good luck friend!