New Question on P0125 Code

[discosophy]

So, I was hoping that this horse was beaten to death already, but apparently, it hasn't been. I have a 1996 Disco V8. code P0125. Insufficient coolant temp, etc. MY thermostat is only a year old; my sensor ohms at 260 cold and drops to 202 after running 10 minutes, so I assume that's good. My coolant level is fine. That said - my temp gauge only moves when it gets really hot (like when I lost my drive belt). My coolant level is fine. So, code p0125, engine does seem as if its running hot, but individual components test out ok. What gives? Should I just replace the thermostat again for kicks and see if it goes away? Anyone have a ohm reading spread on a working CTS? Any tips/suggestions/slams for being an incompetent shade-tree mechanic are welcome. Thanks!

[jafir]

you could test the thermostat outside the vehicle.

RAVE lists the resistance of the coolant temp sensor:

Engine coolant temperature sensor (ECT Sensor)
This sensor consists of a temperature dependant
resistive metal strip. The resistance of the strip varies
considerably with coolant temperature, i.e. from 28K
ohms at - 30°C to 90 ohms at 130°C, and 300 Ohms
at 85°C. The ECT Sensor signal is vital to engine
running, as the correct fuelling is dependant upon
engine temperature i.e. richer mixture at low
temperatures. If the sensor is disconnected or failure
occurs a default value will be supplied to the system.
The initial default value selected will be based on the
value of the air intake temperature. This will increase
to a nominal warmed up value over an individual time,
programmed for each default value. The fault may not
be evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.

[bmxermike]

I had that same code after my expansion tank blew all the fluid out the seam. Didn't loose all my coolant but just a little, temp gauge creeped then went right back down. Replaced tank, filled collant, cleared the code and it never came back.

But you seem to have the code for a different reason.