1999 Mercury Mystique Owner Guide 1st Printing - Page 12
1999 Mercury Mystique Manual
Page 12 highlights
Instrumentation These temporary malfunctions can be corrected by filling the fuel tank with good quality fuel and/or properly tightening the fuel cap. After three drive cycles without these or any other temporary malfunctions present, the check engine light should turn off. (A driving cycle consists of a cold engine startup followed by mixed city/highway driving.) No additional vehicle service is required.If the "check engine" light remains on, have your vehicle serviced at the first available opportunity. Light is blinking: Engine misfire is occuring which could damage your catalytic converter. You should drive in a moderate fashion (avoid heavy acceleration and deceleration) and have your vehicle serviced at the first available opportunity. Under engine misfire conditions, excessive exhaust temperatures could damage the catalytic converter, the fuel system, interior floor coverings or other vehicle components, possibly causing a fire. 12