weird temp gauge reading

[john]

my mk1 berlingo normal sits at 1/2 way, stopped in traffic it will rise and the cooling fans kick and the temp lowers, the last couple of days however its only been sitting at 1/4, when i stop as usual it will rise to over the 1/2 and cool down but it cools down to 1/4, temp from the heater feels the same as normal, coolant was changed only last year, I'm going to have a look tomorrow but any idea's what i should be looking for?

[miked]

Thermostat not closing properly (warped) would do this. I don't know how easy it is to get to on a berlingo but should be cheap enough to swap it out.
Hang on I'll look the price up.

Edit: Can't find it on Service Citroen site under cooling. But other sites suggest around £10 example for a thermostat so if it was me I'd change that first and take it from there.

[addo]

Check the gauge sender wiring for damage, too. Being a W-reg it will have three connectors on the thermostat housing; pretty sure it's the blue one you check.

[john]

just to update, changed the thermostat and its all good