Erratic temp gauge

ninty

Not sure if this is the right place to post this but here goes,driving home in my Citroen C2 VTR 1.4 and the temp goes to red,stop, wait, switch it on and its back to normal 3 bars. drive on and back up it goes.Wait about 3/4 hour all bars still lit,engine and pipes feel normal to touch coolant ok,continue on home and it stays fully lit for rest of day even though cold.REPLACED coolant sensor,still same.Take out battery overnight to charge as fan staying on after switching off car was running it down. Reconnect in morning ,great no lights,drive about a mile and goes to 1 bar as normal and then it zooms to red back to 3 bars and then to red (on and off).had to go somewhere so drove 20 miles, stays red for last 12 miles,on arrival opened hood expecting terrible things but bonnet cool and engine,pipes all seemingly normal.3 hours later still all lights on.3 points that may be of importance. 1.got ball joint replaced yesterday 2.Filled car up with petrol so gauge was showing full for the first time in ages and 3.The car has only recently been back on road after a year layup but have being starting it,charging battery ect with no problems.Also no diagnostic fault light showing.If anybody has had this specific problem maybe they can point me in right direction.Thanks

iamtony

I don't know the car specifically but I know in my car there is a temp sensor for the ecu and a temp sender which controls the gauge on the dash see if there is another sensor available.

ninty

I feel u could be right as when i disconnected the sensor to the gauge it was still showing on the dashboard.It does look like the coolant sensor starts off right on gauge then the ecu overides it with overheating warning (fact or fiction).Thank you for reply.

Turned it on after 5 hours (completly cold) and no bars showing,would a temp. gauge behave so erratically with a thermostat gone.

ninty

Right found the problem in case anybody else has it,An engine coolant switch gone ,its under the engine coolant sensor behind airbox,impossible to see.Citroen or consort motors had not heard of it until i took picture of it and part number off internet.it controls the guage warning light.Iamtony put me on the right track,thanks again.