Am getting engine code P0135, so thinking this sensor is bad. How big a job is it to replace this sensor? Does the plenum need to be removed to get to it?

Also, is it common for O2 sensors to fail prematurely on this model? Vehicle has 76K miles. Bank 2 sensor 1 had to be replaced at 62K miles. This is beginning to annoy me.

Thanks in advance for any advice.