What if no obd codes are showing

What is your question?

Well first after I had an oil change the car started dinging and a message came on the cash saying oil pressure engine off owners manual. Then the red oil can light starts flashing on and off that is the only symptom my mechanic checked for one codes and none show

What makes this problem better or worse?

Nothing

How long has your 2012 Volkswagen Beetle had this problem?

3 days