Our 2008 Pathfinder (4.0L) threw this code yesterday. After reading the code and learning that it indicates the temperature of the engine is not rising to operating level, I drove a bit for further diagnosis.
As you would expect, the temp gauge never rises more than slightly above the "cold" mark, even at higher revs and lower speeds. The heater blows warm-to-hot, but not as hot as I'd expect.
So I've ordered a new Thermostat and Temp sensor from RockAuto and will replace both. It seems very likely it is one or both, and for a grand total of $30, I figure it is worthy my time to do them both at once.
There are several videos of people replacing these items on Frontiers and Xterra, so I probably won't bother making a video, but maybe I'll have some photos or a write up for other Path owners facing this issue.
Anyone out there have experience with this already?