Yes if your car is hard to start after sitting for awhile or it starts and runs rough until the engine is warmed up then it could be caused by your coolant temperature sensor going bad.
I had a truck that was hard to start in the morning and would have to let the engine run for 20 minutes idling the engine and slowly driving it by just letting it coast around and then it would run a little better but still run rough.
After replacing the coolant temp sensor the truck started like it should and ran great again.
The coolant temp sensor lets the computer know the engines coolant temp and tells it how much fuel and air the engine needs to start and to run properly.
If the engines computer doesn't know what the engine and coolant temp is due to a bad coolant temp sensor then it will not run properly or won't run at all.