FC family
FC_a144_CA_flybackUnstable
Charging adapter fault
What does the FC_a144_CA_flybackUnstable alert mean?
The Fast Charge (FC) Electronic Control Unit (ECU) has detected a critical flyback converter unstable fault. The emergency shutdown will be performed for the charging session.
What you'll see in your Tesla
- Charging adapter fault
- Unplug and retry
What triggers it
FC ECU detects the flyback voltage slews by more than 10kV over a single 10mS period while the flyback is in the drive state.
When it clears
FC ECU set the flyback target mode to OFF.
Potential impact
Charging session may not start or may become interrupted.
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.