So my Eco stop/ start wasn’t working. Car was taken to dealer and an overnight charge spplied to the battery. The battery was delivering 97% power out and reporting as “Good” - so no change required according to diagnostics.
Despite the above the dealership wanted to charge me £300 for a new battery as the “technician” insisted this would cure the problem(battery not covered by Jaguar extended Wsrranty). After dialogue with the Service Person I requested them to check carefully what “Inhibit” was holding out the Eco system. Service Person returned and insisted changing the battery would solve thr problem - it slways does!!! I thren requested they use a new battery from Service stock as I was totally unvonvinced that replacing the battery was the solution. After some persuasion they agreed to do this and hey presto - the Eco system was now working. Ok, now please put the old battery back in the car - hey presto Eco system now working with the old(perfectly good battery).
For anyone experiencing Eco issues re-setting yhe Battery Monitor System(happens when battery is changed) also resets the other inhibits actually causing the problem.
Moral of the story - If your desler tells you chsnging the battery will sort the problem on the Eco system he is kind of right. But before you part eith £300/ $400 - ask him to slip the old battery back and check if it’s still working.
it’s fairly clear that the dealerships have limited diagnostic skills/ training.
i have a lot of experience in control systems and was confident to argue the case with the dealer.

Thought it was worth sharing with you.