Citroen relay temp guage issues

[Wynn134]

Morning all

I have a 2010 Citroen relay 2.2 puma engine with 70k miles on.

On a recent trip to Liverpool, I found the temp guage was not moving for the duration of the journey, around 1 hour 30 minutes. until 15 minutes from the docks, where the guage decided it was going to start moving to around the quarter mark on the guage.

On the return journey a week later (van had been sat all week and not moved) it was the same situation but would pass the quarter mark to around 3/4 and then would drop and then rise.

It hasn't used any coolant at all so can say that the head gasket is okay and there is no white gunk in the oil cap either.

It was circulating the coolant as we had hot air and then we switched back to cold and that was fine.

I initially thought it to be a sticking thermostat so have since replaced it and replaced the coolant but to no avail its still doing the same thing.

I've stuck a diagnostics computer on and it's showing no error codes, I can also see live diagnostic so took it for a drive for around 1 hour, temp was sat at around 68 to 69 on a mild day and then left the van to ideal to around 78 degrees, temp guage was moving but not anything it was previously when the temp guage was working where it would happily sit in the middle after about 15 to 25 minutes or so.

I have also replaced the expansion tank cap to see if this was an issue, which it isn't.

The only other thing I can think is the coolant temp sensor has failed but its a right pig to get to, the only way I can see how to get to is to remove the fuel pump and the thermostat and go from there.

Has anybody else had this issue with the guage not moving and has any body else tried to remove the coolant temp sensor ?

Any help or information would be helpful.

Kind regards

Will

[CitRel93]

Hi, I have exactly the same issue and suspect thermostat staying open? - did you get to the bottom of it?

[PaulC5]

If the thermostat is stuck open the radiator top hose will warm up as the engine warms and not wait until the engine gets to the thermostat rated temperature.

[CitRel93]

Mine heats up to half guage over 5-10 mins and then starts to drop off back to not showing on the guage. - with an OBD scanner on it, shows temps heating up to 69ish and then dropping back to 58. the needle will climb to about quarter on the guage under heavy engine load but then fin its way back down. A digital thermometer gives the coolant in the top hose as very similar to OBD readings so I suspect its a thermostat issue and not a sensor?