What exactly is this P0141 ?

My brothers Highlander Check engine went on , I scanned it and the read out was P0141, I checked it out but I really don't understand what it means by heat something if you guys can help me like always i will really appreciate it thxs. 02 SENSOR HEATER CIRCUIT MALFUNTION ( BANK 1 SENSOR 2 ).

 

P0141 is generally a "catalytic converter inefficiency" problem. Meaning it can be any of a dozen different things: O2 sensors, bad cat, exhaust leak, etc. It means the O2 sensor isn't reading the proper O2 levels I think. So either you have a bad sensor, leaky exhaust, or bad cat normally. I had to replace the cat on my Corolla for the same code as replacing the O2 sensor after the cat didn't fix it.Same code again, and I'm not paying for a 3rd cat so I'm looking into an O2 sim.

 

Thxs. my friend I think I will be replacing the O2 sensor.