Question about ECU update and cooling fan temperature logic (EP3C / C3 A51)

[NitroCharger]

Hi everyone,
@GiveMeABreak

I hope you're doing well. I'm reaching out for some advice regarding my Citroën C3 (2012, A51 chassis, EP3C engine with eat5 transmission).

Recently, I discovered that my car received a factory ECU update in 2019 (done by the dealership), and since then I’ve noticed that the engine cooling fan only activates at 105°C. I'm concerned that this update may have changed the fan activation logic and increased the engine’s operating temperature.

Here’s a summary of what I observe:

The fan does not start at 98°C (as I understand it used to on earlier software).

It only kicks in at 105°C, even under light load or idle conditions.

With the A/C on, the fan starts immediately (which suggests the fan hardware is OK).

I monitored this using an OBD scanner over several driving sessions.

I'm trying to understand:

Was this change intentional by PSA to increase fuel economy or meet new standards?

Is it safe to operate the engine consistently at 105°C, especially in hot climates?

Is there any way to restore the old fan logic (e.g. first speed at 98°C, second at 105°C)?

Could a custom firmware or reverting to a previous ECU version help?

I'm a bit worried about the long-term impact of running this hot, especially since I take good care of the engine and want to preserve it.

Any advice or information would be greatly appreciated. Thank you in advance!

Best regards,

[NitroCharger]

viewtopic.php?t=61749

The data from my car doesn't match the values mentioned here. I usually see an oil temperature of around 105°C and a coolant temperature of about 105°C in traffic. This makes me suspicious that there might be a malfunction in my 12-year-old car, or that these temperatures could be a result of a software modification.

[PaulC5]

I do not know how the fans are run at the 2 speeds but maybe whatever starts it at the lower temperature is faulty - maybe a wiring/connection fault or a relay if there is a separate one for each speed.

[NitroCharger]

When I set my speed to 85 km/h, I noticed that the engine temperature drops to around 80–85°C. I realized that this helps keep the engine cooler on long trips and also reduces fuel consumption. I learned this from a Russian forum, tried it, and it worked.