DTCs (or computer codes) don’t tell a technician if a part is bad, they only indicate that the Computer or Module has seen something it didn’t expect in a certain circuit. The problem may be the part, but it could just as easily be an issue with the circuit’s wiring or even need a computer software update (just like Microsoft). Sometimes codes are set when the problem happens to be mechanical, like a vacuum leak or timing chain and even LOW OIL, creating conditions that cause components to generate a signal the computer doesn’t like.
This is where the ability of technicians to determine what additional tests are needed to accurately interpret both test results and computer network data, comes from extensive training and experience. Today we use very expensive scanners to “see” what the vehicle computer sees and observing Multi Meters or Digital Oscilloscopes, looking at wave patterns and voltage spikes and current ramping in real live time. Combining test results with expert knowledge can lead to an accurate diagnosis.
If you don’t have a good relationship with an auto repair shop you can trust to properly diagnose your car’s problems, consider Extra Mile Auto Service where we determine the underlying problem that’s causing the symptom.