Engine Light

Hi, I'm one of the auto experts on RepairPal's Car Genius team! Sorry to hear you are having issues with your 2013 Audi S4. O2 sensor codes can sometimes be misleading as they sometimes point to a sensor that has failed but more often than not they point to either a failed/failing catalytic converter or an issue with the engines air/fuel ratio. The fact that you are seeing a damaged wire underneath the car is definitely concerning and may be related. Though without first identifying what the wire is, it is difficult to say. If it is a wire for the O2 sensor, what caused the damage? If it’s cut or chewed through by mice it’s less concerning than if it is melted. If it’s melted you’ll want to know what caused that rather than simply repairing the wire. Because there are so many factors at play here and so many reasons why O2 sensor codes can set, I’d strongly recommend bringing it to a shop to have properly diagnosed before swapping parts or messing with wiring. If you need any further advice or would like help finding a trusted RepairPal shop in your area or even getting an appointment booked, please feel free to call us at 877-913-1554 or check out https://repairpal.com/certified