hi we have had a 2001 picasso recently been driving well, went for a long drive 2day and as we get to 40 miles the temp suddenly shot up and a warning came up saying ''stop engine overheating'' so we did, when we checked car there was no signs of overheating at all, and the fans were working fine, we continued with journey with the warning on but no overheating happened. we stopped for an hour then warning had gone off, but on way back once we hit 40 miles the same thing happened again. does anyone know the answer to this problem, thanku
we dont think its thermostate as the car isnt actually overheating its just a warning sign coming up

would be wise to replace thermostat or have the system flushed

Could just be a sticking thermostat. Take it out and suspend it in a pot of water on the hob. It should open fully just before the water boils. While you've got it out flush the cooling system and refill with a good anti freeze mix.. Haynes manual gives the best tips for this. They say you need a 'header tank' to refill, but l did not when doing mine.

NO it is not the thermostat. l have the same problem on my 1.4 Berlingo for the last two years, except it is now starting to get worse.
What happens is that as the engine temp goes over half way the gauge suddenly shoots into the red & the warning sound beeps. On my car, after about a minute it then returns to normal but then happens again a short time later.
l think u have a similar problem (my Berlingo is an 02 plate)

My local Citroen garage were useless & so were Citroen. They were unable to diagnose the exact problem & after a week eventually came up with two possibilities. One item was about £450 to replace & the other was about £250. Now this was the thing that really annoyed me:- If we fit one item, & then we find it is not that causing the problem, then u will have to fit & pay for the other item as well!!!!
So that is why 2 years later my car still has the same problem.

You will find that in the winter period the problem goes away..... almost.

One thought is that u could have an air bubble trapped in the cooling system somewhere. If this is the case, u need to get it out because u could be gettting localised heating in one spot.

You could try seeing if the computer has recorded a fault.

It seems strange that it occurs after 40 miles, as the engine should reach normal temp well before then, & to have it happen twice seems to indicate there is some logic to the message. Does the gauge normally register aroudn 82°C (which is a typical thermostat temp)? If it is lower, it could be that the thermostat is stuck open or broken. Another car l worked on had a check the ecu did when u had travelled about 20mins at around 100 km/h (which should mean that the engine is up to temp) to ensure that the coolant was at the expected operating temp. Could be ur car has done this, found it incorrect & advised u by the warning lights?

It could be that your temp sensor is blown or it has a contact problem.
Also can be caused by water pump. Hard to say without looking into the engine.
Citroens have a tendency to have annoying little electronic failures. :-(