Hyundai Repair: problem with my hyundai, hyundai elantra gt, hyundai elantra

Question
i have a hyundai elantra gt 2003 my engine light came on i got the code it is 0139  so can you tell me the problem and where is it  on my car  please

Answer
P0139 indicates the downstream oxygen sensor is slow to respond to changes in fuel mixture.  The most frequent cause of this trouble code is a leak in the flex pipe area of the front exhaust pipe and converter assembly.  If you have this problem and the vehicle has under 80,000 miles, this issue should be covered by the federally mandated 8 year/80,000 mile emissions warranty.

If there is no leak in the exhaust, the problem is almost certainly with the downstream oxygen sensor located in the front exhaust pipe.