overheating

I recently bought a 2003 c3 1.4 petrol and it runs fine but there are no bars on the thermostat showing but if I'm sat in traffic it will suddenly jump up to full when I pull over the fan does run for 5 minutes or so even though the engine doesn't feel very warm the head gasket was replaced apparently but before I go through the expense of replacing it again was wondering if it could be a sensor any advice would be a great help thanks

Welcome to the forum fawcettc3

fawcettc3 wrote:the head gasket was replaced apparently but before I go through the expense of replacing it again

No one would advise you to change a head gasket if the engine was only not heating up or cooling correctly.

fawcettc3 wrote:I recently bought a 2003 c3 1.4 petrol and it runs fine but there are no bars on the thermostat showing but if I'm sat in traffic it will suddenly jump up to full

Sounds like the coolant is not circulating correctly, probably and air-lock or some such problem. You say its had a new head gasket, so it needed new coolant. If this has not been done correctly, you may well have problems. There is a thermostat which can be causing trouble too, worth checking it out if you are going to do the coolant again.

Procedure for refilling the coolant on the C3 https://citroenc3owners.com/citroen-c3-t ... t-t40.html

fawcettc3 wrote:if it could be a sensor any advice would be a great

Yes, could be engine temperature sensor? Its cheap enough and not difficult to change. There are several possible ones fitted to the C3, so take a look at eurocarparts and enter your reg into the box to find the right one.

all the thermostat lights came on again and I squeezed one of the pipes the fan went off and so did the lights back down to 0 I checked the water and it looks filthy like its never been changed so I will try what your saying at the weekend and let you know if its cured thanks very much for replying