content: Which parts of cars are illegal to work on oneself?  This is just the price we pay for taking advantage of newer technology in vehicles. It gets more and more advanced and the average non-mechanic and non-programmer just aren't going to have the requisite knowledge to safely work on their own vehicles. People would rather have cars that automatically tell them if they have low tire pressure and have computer-controlled engines that maximize fuel efficiency and engine power than having the ability to work on their own cars.