Just the Facts: Ignition Coil-on-Plug (COP) What does an Ignition Coil-on-Plug coil do? In Coil-on-Plug technology, since each cylinder has a coil, the PCM controls individual cylinder firings for more precise ignition timing, reduced emissions and better fuel economy. Where are these sensors located? The Coil-on-Plug (COP) coil is usually mounted on the top of the cylinder head just above the spark plug. The coil is connected to the spark plug with a stainless steel spring connector and protective insulating boot. Will a malfunctioning Coil-on-Plug illuminate the check engine light or affect vehicle operation? Yes, a failing Coil-on-Plug can illuminate the MIL, and is likely to create an engine misfire condition. What are the common causes of failure? Typically the COP coils fail due to exposure to high heat moisture and oil as they are mounted on top of the engine. The coil windings can fail due to the large flow of amperage. How to determine if Coil-on-Plugs are malfunctioning. The output of the Coil-on-Plug coil can be determined by inserting a spark tester into the coil boot and cranking the engine over. Occasionally the wiring to the coil or the PCM can fail therefore the primary circuit to the coil should be checked for proper voltage and computer control. What makes BWD Ignition Coil-on-Plugs the best. BWD Coil-on-Plug assemblies are manufactured from the finest components for optimum performance and a long service life under all operating conditions Neodymium in the core creates the strongest magnetic field and produces max high voltage output at all speeds High dielectric epoxy is injected into the case and pulled into a vacuum to eliminate air pockets and prevent moisture intrusion or thermal breakdown BWD’s reinforced bobbins prevent voltage flashover for an extended service life View our 21st Century Tune-Up® video video Back to Just the Facts