Interesting problem.
My check engine light has been lit up when initially starting
car in morning. The light will stay lit up until the 6th or 7th
start of the engine and then will remain off until the following
day when the same predictable routine will occur, that is, the
check engine light will remain on until about the 7th turn of the key.

I check for codes, and it seems that the problem may exist with the
ect sensor or wiring. But, the problem seems too intentional. Almost
seems to be a computer issue where the computer senses a sensor problem
and allows the car to be turned on/off a certain amount of times and
then turns the check engine light off. Just a guess.

This problem is so predictable that I can start the vehicle, the check engine
light will come on, and after the seventh start the lamp is off, indicating
no problem. I have to almost eliminate the ect sensor because of the
constant frequency of the check engine light turning off, despite the code.
Also, the car runs just fine with or without the light on. There really
are no issues outside of the check engine light.
Any thoughts??