yes I'd agree that replacing the temp sensor is the next step as it controls the fans and also produces the signal to the gauge so in fact the engine may be warm enough? but the gauge is giving a false reading
in that case either the engine really isn't warming up or the sensor is faulty
I'd suggest the next step is to make a measurement of the engine temp with a thermal probe to confirm what temperature its actually reaching
as its possible that the thermostat is faulty so it may need replacing
do you still need help?
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