FC family
FC_a129_CA_flyback_HW_OC
Unable to DC Fast Charge
What does the FC_a129_CA_flyback_HW_OC alert mean?
The vehicle is unable to begin CHAdeMO DC fast charging because the fast charge (FC) electronic control unit (ECU) detects a hardware overcurrent event during flyback.
What you'll see in your Tesla
- Unable to DC Fast Charge
- Contact charging station operator
What triggers it
The FCU ECU detects that the flyback current is over the alert threshold.
When it clears
The FC ECU detects that the flyback current is within expected bounds.
Potential impact
DC fast charging is unavailable.
Affected models
Cybertruck
Model 3 2017-2023
Model 3 2024+
Model S 2021+
Model X 2021+
Model Y
Model Y 2025+
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Alerts like this reach MyTeslaMate through your car's Tesla telemetry API. MyTeslaMate logs every alert your Tesla reports and turns it into readable history and real-time notifications — hosted TeslaMate with no server to run.