Check engine light flashes and turns off

#1
My wife’s 2011 Corolla LE has the check engine light flashing after starting the car and shuts off after a few flashes. I changed her oil every 5000 miles and she just rolled over 120k so I changed her oil today. Is there a flashing reminder at 4500 that stays steady at 5000? Could it be something worse? Thanks.
 
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