Service engine has started blinking on and off

How To Reset the Service Engine Soon Light in a 1999 Buick...

1. Put the key into the ignition and turn it to "Run." Don't start the engine.
2. Press down slowly and fully on the gas pedal, then release it. Do this three times in five seconds.
3. Watch for the "Service Engine Soon" light to start blinking. This indicates that the system is resetting itself. ...
4. Start the Century's engine

Service Engine Soon

If the Service Engine Soon indicator light stays lit after you've started the engine, the On Board Diagnostics system (OBD) has detected a malfunction of the vehicle emissions control system. Contact your authorized dealer as soon as possible.
If indicator light is blinking, an engine misfire may be occurring, which could damage your catalytic converter. Drive in a moderate fashion (avoid heavy acceleration and deceleration), and have your vehicle serviced immediately.*
The Service Engine Soon indicator light illuminates when the ignition is first turned on (prior to engine start) in order to test the bulb, as well as indicate whether the vehicle is ready for Inspection/Maintenance (I/M) testing.
Normally, the Service Engine Soon light will stay on until the engine is cranked, then turn itself off if no malfunctions are present. However, if after 15 seconds this light blinks eight times, it means that the vehicle is not ready for I/M testing.Check this link out Gary.
https://owner.ford.com/how-tos/vehicle-features/dashboard-instrument-cluster/warning-lamps-and-indicators.html

if your talking bout check engine light or ses meaning service engine soon light is blinking u have a cylinder that isn't firing, usually cause by ignition coil, but fuel injector, crank sensor can cause it but most times its a coil u can stop at any auto parts store get the check engine light read

This is most likely a misfire. When the light blinks under acceleration it is telling you the engine is in serious need of service, which doesn't necessary mean that the engine is in serious trouble. Have your OBDII port and codes checked. Your local parts store like AUTOZONE will do this for free.

Engine needs service immediatelly. If Service Engine light starts to blink, it's about to stop completely.

change ur battery

tuneup either u have a bad plug wire or a bad plug sometimes the coil pac could be breaking down but im leaning toward tuneup.

when your car is shaking and the light blinks thatmeans its misfiring,not running on all cylinder,,,

i assume this car is automatic the o/d light is the overdrive light which is controlled by a little button on the gear select lever and usually service engine light comes on when it is due to be serviced like every 5,000 km or so hope this helps regards Jim