What cause the O/d light blink - 1998 Ford Windstar

The D3 light on your car is likely the "diagnostic" or "service" indicator light. When this light is blinking blue, it typically indicates a problem with the car's diagnostic system. The problem could be with the car's emissions control system, engine control system, or another electronic system.
It is important to have a professional diagnose this issue as it could be caused by multiple other issues and a proper diagnosis is needed to find the root cause and prevent further damage to your vehicle.
Here are a few steps you can try to troubleshoot the issue:

1. Check the owner's manual for the specific meaning of the D3 light blinking blue, as it might have a different meaning depending on the make and model of your car.
2. Check the gas cap, make sure it is tight and properly sealed. A loose gas cap can cause the light to come on.
3. Try to reset the light by disconnecting the battery for a few minutes, this can clear any stored codes and turn off the light.
4. If the light is still on after trying the above steps, it is best to take your car to a professional mechanic or dealership service department for further diagnosis and repair.

Check battery and fuses.

yes it could cause the blinking red light.

Check to make sure the correct bulbs are in the sockets and as Karl said check the grounds. An incorrect bulb can make one blink faster and a bad ground can cause one to blink that way.

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

When the light blinks it in most cases means a misfire is detected.
If the spark system has recently encountered any water this is one of the number one causes for the light to blink.
Ereae the code after you find out the cause if you can,Good luck,Gary

blinking light means engine is misfiring. continuing to drive will severely damage the engine. The O2 should not be related to your engine misfiring

check the relay and blown out bulbs will cause the lights to blink fast or some to stay on. one bad bulb will cause the problems.

Sounds like a ground problem on one or more of the light modules.