1996 Mercury Sable Owner's Manual - Page 108

Service engine soon light This light comes on when you turn the ignition key to ON, but should turn off when the engine starts. If the light does not come on when you turn the ignition to ON or if it comes on and stays on when you are driving, have your vehicle serviced as soon as possible. This indicates a possible problem with one of the vehicle's emission control systems. You do not need to have your vehicle towed in. If the light turns on and off at one (1) second intervals while you are driving the vehicle, it means that the engine is misfiring. If this condition persists, damage could occur to the engine or catalytic converter. Avoid heavy acceleration and have your vehicle serviced at the first opportunity. You do not need to have your vehicle towed in. If the light turns on and off on rare occasions while you are driving, it means that a malfunction occurred and the condition corrected itself. An example of a condition which corrects itself occurs when an engine running out of fuel begins to misfire. In this case, the Service Engine Soon Warning Light may turn on and will then set a Diagnostic Trouble Code indicating that the engine was misfiring while the last of the fuel was being consumed. After refueling, the Service Engine Soon Warning Light will turn off after the vehicle has completed three consecutive 81