[nradov]

An ODBII is helpful for basic stuff but it doesn't get you very far with modern cars. Most manufacturers now have specialized proprietary scanners which are needed for any complex repairs, especially for anything electronic. Those scanners are extremely expensive and sometimes only sold to authorized service centers.

[fragmede]

Are these manufacturers called BMW, by any chance? They sell this authorized "computer module" replacement part for $400. But if you take it apart, there's a 50 cent fuse inside that was blown. Replacing the fuse does no good without access to the proprietor BMW software, because the module will refuse to work after the fuse is replaced until it is reset using their software. Which means you have to pay for a whole new module. However not all manufacturers are like that. After I change the oil on my Honda, there's a silly little dance to reset the oil life indicator, but nothing too crazy. The Toyota Corolla is a favorite for self-driving car enthusiasts due to the hackability of its lane-guidance system into something fuller. I'm also disappointed in some of the directions the future has taken us (it's frustrating to me how hard it is the replace user-servicable parts inside a lot of laptops, eg Apple), but not all manufacturers are the same and talking about the situation as if they are is too abstract to be useful, say, when looking for your next car.