No maintenance. You can in theory, regularly check for system updates and install them. I've an Ultegra Di2 as well as XT Di2, I've never done system updates. My attitude is they work perfectly so why ?. As well the Shimano e-tube software was futzy when I first started using it, not sure Shimano fixed stuff, not wanting to find out. The road system I've had 4-5 years, never touched it. The nice thing about electronic is other than charging the battery(s) they need no maintenance.