Water Temp Guage Question + Normal Running Temp?
 

I'm having problems with my temperature guage - in that it seems to go off randomly, the light and the buzzer both go off. Yet the needle on the guage stays at the 9 o'clock position.
I have checked my coolant and it is at the right level, I have had the Apexi Power FC ECU + computer fitted and mapped very recently (as well as an engine rebuild + other mods). The water temperature as measured by the FC computer unit is a constant 85 - 90c. Is this temperature normal and is it that my temperature sensor is knackered or an air bubble is affecting it, as some other threads suggested?

Another thing is recently my heater matrix decided to go pop but I have had the matrix piping bypassed - could this be affecting the sensor?
I know that there has been some previous threads on this before, but I am very concerned about this and I could do with some comprehensive answers.
Many thanks.

I would check the sensors and make sure they're functioning first. The coolant level sensor, the water temp sensor for the ECU, and the water temp sensor for the gauge are three different, individual sensors. I would check the wiring and connections on the water level sensor first.

The sensor for the water level is the black sensor screwed into the front of the water pump housing. A single wires comes out of it towards the front of the car. Then the wire turns a 180 degrees and goes into the mess under the UIM. Check the wire right at the sensor to see if it's deteriorating, rubbing on anything, completely broken, etc... After that I would check the other end of the wire where it plugs into the engine harness, see if the connection is loose, covered in oil, etc... After that, check the sensor itself to see if it is up to spec (see the service manual, you probably just need to check the resistance of the sensor or something with multimeter).

If it seems the water level sensor is good, then check the water temp sensor for the ECU (screwed into the back of the water pump housing) and then check the water temp gauge sensor (screwed into the driver side of the engine block, right next to the oil pressure sensor).

- Andy

Okay, thanks for that - i'll give it a try.

Where are you checking your water level at ? If it's in the recovery tank this would explain why your alarm is going off and your level appears to be ok. The water level alarm sensor is in the thermostat housing (located next to the air pump) If your heater core went out and you bypassed it, some air may have gotten into the system and a simple burping of the coolant system maybe all that is needed.