Alternator Failure and Stop & Start Failure error message

Issue: I recently got both the error messages in the title on my 2016 California T. Initially I was stumped, car was driving & performing perfectly, alternator was charging perfectly, and the battery was in perfect condition. I tried various battery disconnections and resets etc, but nothing worked. Tried pulling codes with an OBD reader, but no codes. I searched the archives & no solution, so thought I’d make a long post in case anybody searches this problem in the future. I have also consolidated all the battery reset steps mostly already posted elsewhere but with the addition of the Battery Monitor Calibration procedure I have not found posted.


Solution: I was gearing up for a dealer visit, when I got an excellent steer from user James CLN who pointed me in the direction of a fuse on top of the battery. I discovered “F-P035 10 Mini-fuse for battery state of charge sensor for vehicles with Stop&Start System” (highlighted in green in the photo).

Basically, if you have HELE there is a standalone circuit with an in-line 10A fuse that sends voltage to a battery monitoring system. If there is a problem with that fuse then the system thinks the battery is not charging properly and deactivates the HELE system and throws an error message on the display panel.

In my case, someone had changed the battery and left that fuse dangling in the engine bay, where it accumulated moisture and corroded. I cleaned up the connectors, changed the fuse and problem solved.

There is also a battery sensor on the negative terminal. That sensor needs to be recalibrated whenever you change the battery. In fact, I learnt that if you have a HELE equipped car there are no less than 3 distinct systems that require a specific procedure depending on if you disconnect the quick connector or the main battery earth pole.

Interestingly, if you have HELE and use the battery quick disconnect, the battery sensor is not disconnected, and continues to monitor the battery condition.


Battery reconnection procedure:

For the Body Computer and general systems
1. Remove key from ignition
2. Connect battery
3. Wait minimum 1 minute
4. Turn ignition key to position 2, do not start engine
5. Wait minimum 1 minute
6. Before starting the engine: close both doors and close the luggage compartment lid; unlock and lock the doors using the remote control; open the luggage compartment lid using the remote control; adjust the clock (date and time on instrument panel); close both doors and fully raise the driver side and passenger side windows to their upper limit; check that the windows move down to the “target position” when the doors are opened

HELE battery sensor calibration
7. Start the engine for a few minutes then switch off the engine
8. Leave the vehicle stationary with the engine off for at least 6 hours.
9. DO NOT connect the vehicle to the battery conditioner.
10. DO NOT disconnect the battery.
11. After 6 hours, drive the vehicle for at least 20 minutes.

The self-acquisition function of the Motronic engine management system
12. Leave the engine idling for approximately 10 minutes in the following conditions: engine at idle speed; water temperature stabilised; current consumers switched off (lights, windscreen wipers etc.); air conditioner off.

I hope this post helps someone in the future, I doubt I will be the only one to experience corrosion with that fuse. I’ve posted in Technical Q&A because I think this might also be relevant to all contemporary Ferrari with HELE

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