O2 sensor

My friend has a 2005 Elantra which is running a little rough when she
accelerates. I’ve check the OBD codes and the only thing tripping the
computer is the O2 sensor. When I looked more into her car they have 2
O2 sensors, and the meter didn’t specify which one would be tripping
the computer. So now I have a few questions.

first. Are there different symptoms for both of these 02 sensors to
tell me which one is tripping the computer?

second. Would an O2 sensor really effect the acceleration enough to
make the car stumble at times? Or should I start looking into bigger
issues?

 

An 05 should still be under warranty if it has less than 60,000 miles.
The 02 sensors may be under the emission warranty which is even longer.

 

The OBD code specifies which sensor's signal the ECM doesn't like, and it
also specifies why the computer doesn't like it. What was the OBD code?

While it's possible for an upstream oxygen sensor to cause performance
issues, that's very rare on Hyundai. Again, I'm curious to know the
trouble code, but my gut instinct is that your performace issue is
elsewhere, such as low fuel pressure or worn plugs/arcing wires.

The downstream oxygen sensor cannot cause performance problems. Its sole
function is for the ECM to compare it's signal to the upstream sensor for
the purpose of monitoring catalyst efficiency