It's the manufacturer's way of keeping their emissions figures "accurate". Mine is disabled permanently, but this is due to it having an issue and stalling on the restart. After a couple of stalled restarts the ECO stays off permanently until I turn it back on. Even after turning engine on and off and few times. After changing oil and filters in Citroen C4 Picasso you can reset service reminder (spanner icon) yourself. You don't need diagnostic interface or to visit PROBLEM: the owner says there's a problem with the eco mode. He says it doesn't turn on and can't be activated. - How much to fix? Do I have to take to a mechanic, or is it more computer related? Can I fix on my own? - Is this a common problem? - Can the car be driven without the eco mode? The car is a 2015 model, its the very basic model. i8Wub.