Posted on 4/17/2012
If your “check engine” light is on, something is wrong. These lights didn’t exist back when vehicles were tuned every 5,000 to 10,000 miles and it was a difficult procedure to correctly tune an engine. I often compared that task to being the conductor of a symphony, making sure all the different components of an engine were perfectly timed and working in concert with each other. But tune-ups like this are no longer needed, because everything in an engine is controlled by an onboard computer called an electronic control unit (ECU). The ECU looks to many components for inputs to get the firing and air/fuel mixture correct. The greatest ability of the ECU is self policing. It checks the amount of air coming into the engine, burns it and takes samples after it leaves the engine to make sure the air and fuel are being burned correctly (and efficiently, reducing air pollution). It looks for misfires in the engine and, if there are any, activates the check-engine light. On newer vehicles ... read more