Me, I'd get another car. Those things fall apart at that age and yours is starting to

I agree with Scotty, it's time to look for another car.

IMHO, it's not the best use of your finances to put money into a car that has little residual value and likely has other issues looming. 

I've owned two Elantras (2002 and a 2010).  Good little cars, but they did tend to wear out as they aged and/or racked up the miles.   It's impressive as heck that the 2007 has been chugging along with almost a quarter-million miles, but I suspect it will need more and more attention in the near future.  Depending on the cause of the codes, it might be cost-prohibitive to even fix what's wrong at the moment.