2005 Citroen Relay 2.8 Hdi Water Temperature Gauge Always Shows Cold

[bobmcduk]

Hi, I've got a problem with my 2005 Citroen Relay 2.8 HDI water temperature gauge on the dash board, it always shows cold, even when the engine is warm and the heaters are pumping out warm air. As part of the diagnostics I am trying to locate the temperature sensor on the engine but have currently been unable to find it, do you have any idea where it is?

 

Thanks in advance.

 

Bob

[paul.h]

Welcome to the forum.

 

If the gauge is still showing cold then chances are the thermostat is faulty, even though there is warm air in the heater. It should not open until about 82°C so you could feel the radiator top hose and it should not start to get warm until the engine is hot. If it opens before then it needs replacing. If it does need replacing the heater will give out hot air rather than warm once a new one is installed.

 

To check the temperature sensor it is best to use a code reader with live data to see what temperature it is giving, should be outside temp before running the engine first thing and then be about 90°C or more once the engine has warmed up. Whilst doing this you can check the temp at which the radiator top hose starts to warm up to see if the thermostat is faulty.

 

The temperature sensor could be on the back of the thermostat housing but there may also be one here for the air conditioning (blue connector. It stops the air con on high temp) and a 3rd one at the bottom of the radiator to switch the radiator fans - first speed at 95°C, 2nd speed at 99°C.

[bobmcduk]

Thanks for the fantastically helpful reply, I'm not around for the next week but will use the info you've given me to run some tests, when I'm back.