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,
Question about ECU update and cooling fan temperature logic (EP3C / C3 A51)
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Re: Question about ECU update and cooling fan temperature logic (EP3C / C3 A51)
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.
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.
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Re: Question about ECU update and cooling fan temperature logic (EP3C / C3 A51)
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.
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- Posts: 4
- Joined: 19 May 2025, 05:43
Re: Question about ECU update and cooling fan temperature logic (EP3C / C3 A51)
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.