Auto computer diagnostics have simplified the process of identifying and fixing car problems. In the past, simple engine components were wired together in complex configurations. These days, car manufacturers have computerized every component of your car from the fuel injector to the oxygen sensor.
Your car might have as many as 50 microprocessors monitoring pressure, temperature, speed and a number of other things. These processors communicate with your car’s central module, sending messages whenever a sensor notices a problem. The central module saves the ”fault code,” a code that says which processor sensed the problem, and what it measured.
When a fault code has been saved, your ”Check Engine” light will come on. A simple car computer diagnostic test will reveal the problem.
Well, sort of. Because vehicle diagnostic tests reveal problems so quickly and easily, it’s tempting to replace the part in question without identifying the underlying problem.
Take this example. Your oxygen sensor has sent a message saying that your fuel-air mixture is ”lean,” or there’s too much air. This means one of three things: your oxygen sensor is malfunctioning, you have a fuel injector problem or there’s a vacuum leak. You could replace your oxygen sensor all day, but if the underlying problem is a vacuum leak, fuel supply issue or something else, you’re just wasting your money.
Auto computer diagnostic tests make it easier than ever for DIY-ers and inexperienced mechanics to inaccurately diagnose car problems. This wastes your money and your time.
The results from vehicle diagnostic tests should be treated as a compass rather than a direct answer. It gives you the general area of possible problems, and a direction to go. But it doesn’t tell you exactly what is wrong—only an experienced, properly trained and equipped technician can effectively diagnose an engine computer problem.