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Home >> Mazda >> 1991 >> 929 Base >> Repair and Diagnosis >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Self Diagnostic System >> Check Engine Light

Check Engine Light

Also called Malfunction Indicator Light (MIL) by manufacturer, comes on when ignition is turned on. Light remains on for several seconds after engine has started. If an abnormal input signal occurs, light comes on and code is stored in memory. If the abnormal input signal returns to normal, ECU turns light off but code remains stored in memory until cleared. If ignition is turned on again, light will not come on until ECU detects another malfunction during system operation.

NOTE: ECU diagnostic memory is retained by direct power supply from battery. Memory is not erased by turning off ignition but is erased if battery or ECU is disconnected.