E020 displayed; charger indicates ‘phase error’ or ‘phase rotation fault’ on three-phase installations.

Safety first: Three-phase systems are hazardous. Only qualified electricians should work on them.

• Verify wiring: Compare the actual connections at the charger terminal block to the Siemens wiring diagram. Correct any miswired phases.
• Check for phase loss: Measure voltage between each pair of phases and between each phase and neutral. A missing or low-voltage phase indicates an upstream issue (fuse, breaker, or cable).
• Correct rotation: If the charger requires a specific phase sequence, swap two phases at the supply (by an electrician) to correct rotation.
• Inspect terminals: Tighten all phase and neutral terminals to specified torque to prevent intermittent phase loss.

If supply phases are correct and stable but E020 remains, the internal phase detection circuit may be faulty and the control board may need replacement.