E303
Enphase
Phase Current Imbalance Fault
Charger displays E303; app may show 'Phase imbalance' or 'Line current mismatch' (for three-phase capable models).
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Unequal loading on phases due to wiring error, Open phase conductor, Faulty current sensor on one phase, Internal power module failure on one phase
How to Fix / Troubleshooting
High-voltage three-phase hazard: Only a qualified electrician should work on three-phase circuits.
- Verify wiring: Electrician should confirm all three phases are correctly landed and tightened at the charger input and that phase rotation matches Enphase specifications.
- Measure currents: With appropriate tools, measure current on each phase during charging. Large discrepancies indicate wiring or module issues.
- Check for open phase: Confirm all upstream breakers and fuses for each phase are intact.
- Service: If wiring is correct, a failed current sensor or power module on one phase is likely. Replace the affected power module or main board.
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Repair Difficulty
Professional Required
5/5
Required Part
Enphase Three-Phase Power Module / Phase Current Sensors
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