first, I need to state one fact : F1 light on does NOT necessarily mean the system pressure is low, it means it is very very likely the pressure is low. Today, for some misdemeanor of playing with electronics, I have the light on and drive the car as usual with no problem whatsoever. Please also note that this is a rare occurrence, which means in most cases, your system pressure is low when the f1 light is on. My guess: it is a TCU signal that was sent to the dashboard and sometimes the signal just went wrong On to the observation I have today. Background: Challenge Stradale euro version. Galileo scantool (mini leonardo). My CS has never been able to complete a full self learn cycle on the galileo, which promps this thread: https://www.ferrarichat.com/forum/threads/360-self-learn-glitch.564709/ Now, in that thread, from all helpful people, I was able to narrow it down to my pressure sensor as the culprit. Note that I also had a flashing "3" (as in 3rd gear) problem on the instrument panel. So, instead of replacing a possible faulty sensor with messy procedures, I decided to test the sensor in-situ first by replacing the CS TCU with an early 360 TCU that I happen to have as a spare. This will also give me some insight about the flashing 3rd gear indicator. The observation: I replaced my CS's stock CS tcu with a MY02 TCU. I didn't bother to do anything like copy close clutch position or any of that because I am only interested in the self-learn function (The pressure sensor, for that matter). And voila, everything good, the self-learn cycle completed, just like in my Modena. This probably means my pressure sensor isn't bad. Or is it? So I am going to write a letter to Accini to tell them that your software got a problem. And the problem is that it failed to let on the f1 pump when needed. ( in the MY02 TCU the pump is on 90% of the whole time while in self-learn. in CS tcu the pump is on maybe 30% of the time, details please see this thread of mine: https://www.ferrarichat.com/forum/threads/solution-for-f1-pump-overheating-problem-in-ferrari-360.291200/page-2#post-144488259 scroll down to 24000rpm's post) Now, to the flashing "3" problem on the instrument panel. The original observation on my CS with CS TCU is that on the CS, the flashing "3" will only occur when the PIS is set sufficiently loose. Tightening it up (up to the point that it creeps a little when car is stopped) and the flashing goes away, or at least mitigated a little. Now, with the early TCU installed on my CS, the 3rd gear flashing indicator never occurred, no matter what PIS I set, 4,6, 4.8, 5.1 (4.7 is roughly the "should-be" PIS) . NOW THE PROBLEM. As I proceed to try on adjusting the PIS to 5.3 to duplicate the flashing 3rd gear indicator, the self-learn abruptly stopped at around 3-4 gear change. Tried 3 times, all stopped at 3-4 gear change. Immediately after abortion, the f1 light is on and to my surprise, even if I turn of the car and turn the key to ACC , the f1 light is still on. Usually, you can't start the car with f1 light on ,but in my case, the car started. Not just started , it drives like a champ, as usually, not a single sign of problem except that the gear change speed is in line with what the TCU is supposed to fetch(I've driven numerous 360s with various TCUs). Hence the beginning of the post. On a side note, my early TCU does NOT have the parameter for "actuator centering delta" (or similar wording) , while my CS TCU does. In my CS TCU, before the swap , the delta is -4 and sometimes as far as -26. According to FSM , this is out of the supposed range of -3 to 3. I am not sure what , or how I would draw any conclusion from these observations. Just a share of information. Thank you for reading such a long and tedious, verbose post.