The Nissan Path

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?

Since you'll have to drain all or most of your coolant anyways, I'd take the opportunity to change it.

What are the condition of your coolant hoses? If they look like they could use a change, get some hoses and clamps.

Be ginger with the bolts for the thermostat housing. Easy to cross thread, and also easy to drop the bolts and not easy to find them after.

Remember to use the rad fill procedure, and if your vehicle has rear heat, make sure to put the front tires up on ramps and 'burp' the system several times, otherwise you will have air voids in the rear heater lines.

Usually this is caused by a stuck open thermostat. I usually recommend genuine Nissan thermostats and gaskets when possible, as the aftermarket units were usually a little "off" compared to Nissan 'stats on the older Nissans. I'm not sure if the aftermarket units for the VQ engines are any better.

As a follow up, I bought both a new thermostat and a temp sensor. I removed there thermostat and it was obviously broken, stuck open. Replacing it fixed all of my issues so I haven't installed the new temp sensor.

I previously had sir in the system, but had no trouble refilling the cooling system this time. Heaters (front and rear) all working great.

The thermostat is in a tight spot. Be patient if you go at this job yourself.