Hey everyone, I'm new here. I figured this place might be able to help. I recently purchased a 2019 CPO Nissan Rogue with around 36500 miles on it from the dealership about 3 months ago. 1 month in I noticed my temperature gauge go from normal to the C really quick and pop back up to normal again. Didn't think much of it until all of a sudden I go to start my car and the collision detection lights came on as well as the check engine light. I used a code reader and saw it was a p118 code. The car was still drivable and all the warning lights went off when I started the car again about a few minutes later. A few days later I saw the temperature gauge fluctuating again and then while I was sitting idle at a light, the car stuttered and sure enough, the collision lights and check engine light came on again. I called the dealership and they told me to take it to the dealership shop. I took it in and told them about the p118 code and the fluctuating temp gauge. They took my car for about 3 days and called back and said they changed the ECT sensor and that everything was all good now. Sure enough as I'm driving home, the temperature gauge starts to fluctuate again from normal to C normal to C. I called the shop back again and was told that it takes time to recalibrate after changing the sensor. FF a month later the gauge was still fluctuating. The check engine and collision lights never came back though. So I called the shop again and they told me to bring it in. I told them from what I've been reading, it could be the thermostat. So they say to leave it for a few hours and then they call me back saying that they went ahead and changed the thermostat and everything should be good now. So now I'm on my way home again, and guess what? Temperature gauge is still fluctuating from C to normal. So back to the shop. They said their master tech called Nissan and this is only the 2nd time they saw this before. Now they say it's probably the cluster or ECM. So they take my car for about 2 weeks and say they had to change the cluster. I go to pick up the car yesterday and asked are they sure everything is good now? They assured me yes. They did extensive tests, drove around blah blah blah. What do you think happens next as I'm driving home again? I really don't know what to do at this point. Any input would be much appreciated.

They should be able to tell easily enough whether the problem is in the cluster or ECM if they can get it to misbehave with the Consult3+ scanner hooked up to it. Hopefully it won't be a child at the dentist. Given what you describe about the car stumbling, I'd suspect either the ECM or the sensor wiring before suspecting the cluster. P0118 is an "open circuit" code, so a loose pin-fit at the ECM or sensor could easily cause it.

They've changed the ECT sensor, Thermostat, and what says meter on the invoice. (I'm guessing that was the cluster?) 3 separate trips there already. They said to drive it until Monday and if it still persists, to bring it back. At this point I'm thinking they wanna keep charging me for labor and non existent fixes they claim to be doing. It's super frustrating to see the gauge drop from normal to C and sometimes stay at C for up to a minute before returning to normal. They say that all the wiring is ok and it has nothing to do with the connectors. I'm lost at this point.

Yep, "combination meter" is what Nissan calls a cluster. These guys need to pull out their pin-fit tools and check the pins on the sensor and ECM connectors for proper spring pressure. Very often open circuit problems which come-and-go are caused by female connector pins with weak or broken springs. If that isn't it, then chances are you have a bad wire in the EGI Harness or a bad ECM.