Accepted Answer

Hello,even though the light may be off now or turning off and on there will be a code stored in the vehicles computer.Most likely it will be the same fault code.I would have Autozone check the code and see if it is the same fault code,if it is then driving back to the dealer would be the best thing to do this way you wouldnt have to pay for the repair the dealer should cover the diagnostics and repair since you just bought the car(most dealers will so they wont loose a car sale).Running th regular fuel in it shouldnt have set the light off unless it was bad gas.What may be going on is there could be broken or corroded wiring to that o2 sensor or a lean or rich running condition that may be setting this code and turning the light on.What I would do from here is have Autozone look at the car and see if its the same code and even if it isnt then I would drive back to the dealer to have it fixed as I would think they should fix this at no charge to you since you just bought the vehicle.I hope this info helped,if you need anything else let me know,Thanks Pete

Expert:	Pete
Pos. Feedback:	99.0 %
Accepts:
Answered:	9/29/2009

ASE Certified Technician

12 years GM diagnostic Technician/Mercedes Benz Technician