PCS family
PCS_a090_expectedAcVoltageSourceMissing
Charging slowed - Some AC phases not powered
What does the PCS_a090_expectedAcVoltageSourceMissing alert mean?
PCS detects one or more power converter expected AC voltage sources are missing, possibly due to bad utility wiring or vehicle HV harness connection
What you'll see in your Tesla
- Charging slowed - Some AC phases not powered
- Check power source and charging equipment
What triggers it
Charger detects that one or more expected AC voltage sources is missing, possibly due to bad external wiring
When it clears
Charger state machine retries or charge cable is cycled
Potential impact
Reduced AC charge rate or inability to AC charge
Affected models
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.