Understanding Professional Car Diagnostics: Why It Takes Time and Expertise . Andrei here from Main Street Auto Repair in downtown Walnut Creek. We discuss the reality of professional automotive diagnostics, explaining that it requires over $60,000 in specialized equipment and tens of thousands of dollars in training. We demonstrate how proper electrical diagnostics involves hooking up scopes, recording data, and test-driving the vehicle under various conditions (highway, city streets, uphill/do