Overheating Warning, But Engine Temperature is Normal – Citroen C3 1.4

[ismlyldz]

The issue has recurred.
Since I was unable to source the original component, I had to install an aftermarket part.
Could this alternative part be the underlying cause of the problem?
Additionally, I noticed that the issue does not occur when the A/C is turned on.

[PaulC5]

With the air con on the engine fan will be running and probably keeping the coolant a bit colder. You could do with looking at live data to see what the temperatures are on the sensors.

[ozvtr]

I heard from someone who experienced a similar problem that after changing many components, they were able to solve the issue by replacing the fan relays. Could this be possible?

Yes, a problem with the fan control circuit can cause these symptoms. However a problem with the fan circuit will stop the air conditioning from working. But the fan is common to the cooling circuit and the A/C.
If you can afford it, I guess it's the last thing to try.
Could it be a faulty "new" sensor? Possibly. Sorry, but you are going to have to make that call. I would tend to lean toward the radiator fan relay.

[ismlyldz]

Today I tried to do some diagnostics: I monitored the car's behavior by tracking the actual engine temperature using an OBD device.

Here is exactly what happens:
When the car temperature reached 95°C, the fan started spinning at 1st speed.
Immediately after, an overheating warning popped up on the dashboard, and the fan suddenly jumped to the 2nd speed.
After about 5 seconds, everything returned to normal and the fan stopped completely.
I would like to emphasize again that this issue never occurs when the A/C is on. What are your thoughts?

[PaulC5]

With the air con on what temperature does the engine get to since the engine fan will be running for the air con so might not get over 95°C ?

On this year of petrol engine there are 2 engine temperature sensors, one with a green connection and one with blue. It could be the blue one is faulty and needs replacing. There was a similar topic not too long ago and the blue one was faulty. viewtopic.php?t=89004

[ozvtr]

You said that you were monitoring the engine temp on the OBDII scanner when the over temp warning came on the dash.
By "over temp" I assume you meant that all the temperature lights came on?
You did not say what the engine temp read on the scanner. I assume it stayed normal?
To reiterate, all the lights coming on means that "there is a fault in the cooling system". To say it's an over temp warning is a misnomer, as we know that there is nothing wrong with the engine temperature.

PaulC5; the blue sensor was replaced and they got some respite for a while. However that doesn't mean it's good.

You said the radiator fan was running during the event, so the fan circuit is OK (failure of the fan circuit will cause all the lights to come on).
I believe the OBDII scanner indicated normal coolant temperature (yet to be confirmed). So engine cooling system is OK and the "green" sensor is working correctly.
So that leaves the blue sensor.
I can not give a correlation between the A/C system and the fault. It's possible, as PaulC5 says, with the fan running, it's bringing the engine temperature down just enough to not set the fault off.

My suggestion is to disconnect the electrical connector from the blue sensor. Run the car without it and see. Disconnecting it will not affect the performance of the engine.