2010 Hyundai Elantra 197,000 miles

Diagnostic Codes P2626

Just bought this car from a dealer. Runs nice and has almost 200k miles. It has 45 service records.

Only problem is the check engine light is on. I scanned it and it displays P2626. Long term fuel trim is stuck at 15%. From the second I start the engine, idl, and drive, it's always at 15%!

Te scanner app (VeePeak BLU) shows me oxygen sensor 2 is "N/A" and long term fuel trim for bank 2 is always 15% 

I checked the MAF data and it idles at around 3 grams/s, about 8 grams/s at 2500 RPM, and will hit up to 30 grams/s at 4000 RPM but evens out at around 20 g/sec at 4000 RPM in neutral.

I says the codes haven't been cleared in 150 miles. The dealer said they may not have cleared the codes after replacing the fuel injectors, timing belt, and some electrical wiring.

Do you think the 02 sensor code just needs reset? Would the car be "stuck" at reporting 15% fuel trim because of the bad 02 sensor and if I delete the codes, would it show a realistic fuel trim?

What else can I do to find the root cause of 15% LTFT. Is this typical for a 200k mile engine? I want to see what pops up after clearing these codes and don't want to do that if the data would be important to a mecha if I want to take it I to the shop to diagnose any fuel trim problems.

Thanks, and cheers to my new used car!