OBD Code P0599 which coolant?

Hi all,
Yesterday i had the service light come on and off,indicating a minor fault. I used my OBD reader and was given the code P0599. It indicates an issue with the cooling/thermostat system. I checked my coolant meanwhile and its below the minimum level. Apparently low coolant can trigger this issue.
Can anybody recommend which coolant i should put in, and how its done on a C3?
I drive An 06' C3 Desire , 1.4 Litre.
Thanks

Hi
tips-for-any-citroen-c3-f8/coolant-t40.html
The coolant topic

Joshuap03 wrote: ↑Fri Feb 26, 2021 1:20 pm Hi all,
Yesterday i had the service light come on and off,indicating a minor fault. I used my OBD reader and was given the code P0599. It indicates an issue with the cooling/thermostat system. I checked my coolant meanwhile and its below the minimum level. Apparently low coolant can trigger this issue.
Can anybody recommend which coolant i should put in, and how its done on a C3?
I drive An 06' C3 Desire , 1.4 Litre.
Thanks

The engine for that year should not have an electric thermostat (which the P0599 code refers to).
The diesels have a sensor in the expansion tank to indicate low coolant levels but not in the petrol versions.
The above applies for most countries but you haven't said what country you live in.
If your engine does have an electric thermostat it is probably faulty. Otherwise I have no idea where the P0599 code is coming from.
The spherical expansion tank is only a reservoir. It does not indicate the level in the system. Theoretically, if there is any coolant in the expansion tank, your cooling system is full. However, if the coolant level in your expansion tank is going down you have a leak in your cooling system.

As far as the coolant is concerned, if you are not going to drain the coolant completely, just top it up with demineralized water. It's not wise to mix different types of coolant.