Question

2006 kia optima dtc code 2159

Answer 1

2006 Optima does not use code P2159 try to use a different OBD-II reader

P0300 is a misfire code, if you use low octane fuel start by filling up 91 octane from Shell or Chevron and use a good fuel system cleaner.

If you have not have the spark plugs replaced with the correct OEM spark plugs it would also be a good idea to replace them due to the age of the car.