engine light won't go away
 

after buying car the engine light came on and oil light comes on occasionally too. I've had the car inspected several times and no issues found. Oil levels are good. I've had engine light reset and it stays off about a week then comes on again should I replace the sensor or could something else be going on. I get a engine code 51 which is the PROM not sure what could be going on except car is used and car was damaged in front but repaired. Read about someone who had a PROM wire issue after car was repainted could that be an issue here? Also after a month car will occasionally not immediately start turns over 5 to 8 seconds before catching is this related?