Why do AEM Smart Coils overheat or fail, and is it covered by warranty?

AEM Smart Coils are extremely robust and used in top racing applications. When one overheats it is almost always because of too much dwell: the ECU charges the coil for too long before firing, overheating the windings and deforming the case. Dwell is set in your ECU calibration software; more is NOT better. Diagnosis: if the engine never started and the coils distorted, the + and – terminals were probably crossed; if the engine ran for a while and then coils failed one by one, the cause is over-dwelling. Coils damaged by excessive dwell or reversed polarity are not covered by warranty. Always check the dwell values in the AEM coil instructions and send us your dwell settings and photos if a coil fails.