(another) Potential Coolant sensor issue

[rorymonsta]

Hi all, new user here

I have had my 2012 200hp RCZ for a few weeks and have noticed that semi-frequently when warming up my temp gauge is climbing normally, then dropping down about 20 degrees (or at least a noticeable movement/shift in the needle). It then climbs to normal (90 degrees?) and stays there. However when I plug my cheapish scan tool in the live readout of the coolant temp can vary even though the needle is at 90. Today the scanner read 99-100ish over 40mins of driving but the needle remained at 90. I let it idle when I got home for a while at the temp got to 106 degrees and the gauge still read 90. A further concern is that the fan did not come on at any time while it was idling (which is odd to me as my 01 type r Honda kicks in at 90 degrees). I cant verify 100% at this stage because I only started paying attention to it recently. I have looked around and a few people have the fan on too often but couldn't see any with no fan at all.
No codes of Engine light have shown

The AC has been working fine, though I haven't used it much.

Basically the questions are:
Is this likely a coolant sensor or thermostat issue (or both)?
What temp should the radiator fan come on at?
Is it normal for the gauge to read 90 when the temp output on my scanner can be anything from early-mid 80s-106 degrees

 

[NF7]

I have the same behaviour on the 200THP.

ECU does not turn on the vent up to 105 degrees. In this case, when you let it idle at 106 - the vent would kick of in a couple of minutes.

 

[Pedro]

I had a strange issue with my 200 following a cold snap drove the car a few Klms & the temp went to normal then dropped back to 30 & went up to normal after the engine reached had warmed up to normal temp when I returned home I washed all the road film & salt off the car paying attention to the door mirror sensor drove it the next day with no temp fault?

Hi all, new user here

I have had my 2012 200hp RCZ for a few weeks and have noticed that semi-frequently when warming up my temp gauge is climbing normally, then dropping down about 20 degrees (or at least a noticeable movement/shift in the needle). It then climbs to normal (90 degrees?) and stays there. However when I plug my cheapish scan tool in the live readout of the coolant temp can vary even though the needle is at 90. Today the scanner read 99-100ish over 40mins of driving but the needle remained at 90. I let it idle when I got home for a while at the temp got to 106 degrees and the gauge still read 90. A further concern is that the fan did not come on at any time while it was idling (which is odd to me as my 01 type r Honda kicks in at 90 degrees). I cant verify 100% at this stage because I only started paying attention to it recently. I have looked around and a few people have the fan on too often but couldn't see any with no fan at all.
No codes of Engine light have shown

The AC has been working fine, though I haven't used it much.

Basically the questions are:
Is this likely a coolant sensor or thermostat issue (or both)?
What temp should the radiator fan come on at?
Is it normal for the gauge to read 90 when the temp output on my scanner can be anything from early-mid 80s-106 degrees

Engine temp at 90 is normal operating temp anything above or below may send conflicting signals to the ECU as per overheating or coolant leaks if your gauge shows 90 degrees it must be OK otherwise the fan would be activated?

 

[rorymonsta]

I had figured 90 was normal, just odd that the gauge never moved above 90 when the scanner was reading 106, unless there's some sort of dead zone where the guage won't change because 106 is still safe so it doesn't need to indicate anything other than 90 until like 115 degrees or something