Water temp meter stuck at 12:00

[MattInSV]

Hi there. I have a 2000 z3 2.3, 6-cylinder. I just replaced most of my cooling system including the radiator, fan, coupler, water pump, thermostat and housing, belts and tensioner. It seems to be running ok but the water temp meter is now stuck at 12:00 when the engine is running.

I understand there are actually two water temp sensors, but I am not sure which water temp sensor actually controls the gauge:
a) the one on the side of the radiator?
b) maybe something associated with the electrical connection right at the thermostat housing?
c) or maybe somewhere else like in the intake manifold? I didn’t mess with that one.

the sensor in the side of the radiator has a very stubborn connector and it’s possible I could have a broken a wire in the connector end. The little bellows would not slip inside the sensor. It doesn’t appear that any pins are bent though.

Thanks for your help!

 

[Nodzed]

Hi not sure I understand the problem.. when the car is at temp then the gauge will be at the 12 o'clock position. Do you mean it's stuck there even when the engine is cold?

 

[MattInSV]

Hi not sure I understand the problem.. when the car is at temp then the gauge will be at the 12 o'clock position. Do you mean it's stuck there even when the engine is cold?

it’s always at 12:00 as soon as the ignition is turned on

 

[Nodzed]

The sensor on the side of the rad is for the hi temp and activates the electric aux fan at the front of the rad (AC fan) did you change that?
If so then some have an extra bit of plastic in the plug connector area that stops the plug engaging if you look you will see it, I've had this problem. You need to remove it then the plug will seat correctly. Or its the the plug that has the extra bit can't remember, there is a post on here somewhere showing this issue.
If its not this then I would say it the thermostat wiring\plug.

 

[MattInSV]

Thanks I’m a little flummoxed. I didn’t mess with the cylinder head if that’s where the gauge is reading from.

And the 6 cylinder has an electrically heated thermostat but it appears there’s no sensor there? (I don’t know why a thermostat needs to be heated, sounds bizarre)

6-cylinder models utilize an electrically heated engine thermostat. The engine control module (ECM) controls and monitors operation of the thermostat. If a fault occurs a code is stored in the ECM, usually with the description "Map cooling circuit". A fault code can be present yet the vehicle will lack any cooling system issues, such as overheating. If you have this fault code, replace your thermostat and bleed your cooling system. Other symptoms of a faulty thermostat are engine overheating, engine slow to warm up and lack of heat.

And the thing on the side of the radiator is described sometimes as a switch and sometimes as a sensor, but has nothing to do with the temp gauge? I did not change the AC fan.

 

[Nodzed]

Hi I know what the sensor in the rad side is. My point was if it's been changed and it the same as mine and the plug isnt connecting correctly then maybe a circuit is not being made in the system somehow? It was just a thought as you mentioned the plug wasn't connecting correctly. Can only work with the info you provide.

 

[MattInSV]

Hi I know what the sensor in the rad side is. My point was if it's been changed and it the same as mine and the plug isnt connecting correctly then maybe a circuit is not being made in the system somehow? It was just a thought as you mentioned the plug wasn't connecting correctly. Can only work with the info you provide.

Sorry, I don’t. Does the sensor in the radiator affect the gauge reading directly by measurement or only indirectly by switching the AC fan on?