Water Temp Sensor - P0115
Had fault code P0115 appear earlier. MultiECUscan says this is:
"Engine coolant temperature circuit malfunction.
The reason for this is that ECU has received a very high signal from the sensor...."
Now I have done a quick search on here and it seems this could be related to a number of things.
1. Coolant levels; The car had a service last weekend, but I will check levels tomorrow.
2. Water pump; I seriously hope not because it is only 4000 miles old.
3. Thermostat / thermostat sensor.
So my question relates to the thermostat & sensor:
How quickly should the car reach 90 degrees?
I've noticed that the water temp gauge does fluctuate, although I never thought anything of it until now. It never goes over 90 degrees but can take some time to reach it. It also can come down fairly quickly. I have also noticed the fan on quite a bit recently but have taken this down to the hotter weather.
Is there anything I can do to diagnose this using the parameters on MultiECUscan?
Other symptoms my car has which may be related / un-related:
-Rough idle (not on start up, after about 10 minutes of driving)
-Erratic revs at idle.
-Swirl valves on inlet manifold sticking.