What causes the check engine light to stay on, only problem transmission is automatic and will not shift to overdrive.
Once the car is up to running temp the engine can be shut off than restarted and no longer have check engine light on and everything normal, shifts to overdrive again.

Kris

A code was stored in the ECM or TCM. Read the blinking light on the ECM and tell us what code was thrown. I would, also, change the transmission fluid, if it hasn't been changed in 25,000 miles.