Charger shows E04 and will not charge; often occurs after a wiring change or new installation.

Safety first: Only measure live voltage if you are trained and have appropriate tools. Otherwise, contact an electrician.

• Verify breaker and wiring: Confirm that the Sun Country Highway EVSE is on the correct double‑pole breaker size and voltage per its nameplate (commonly 208–240 V). Ensure both hot legs are present and correctly landed.
• Measure supply voltage: With a multimeter, measure L1–L2 at the EVSE input terminals. If voltage is significantly below 208 V or above 250 V, correct the supply issue (panel wiring, utility problem, or wrong circuit).
• Check for loose connections: With power off, tighten all terminal block screws and inspect for heat discoloration. Loose lugs can cause voltage drop under load.
• Test under load: If possible, monitor voltage while the unit attempts to start charging. If voltage sags heavily, the branch circuit may be undersized or too long; upgrading wire gauge or shortening the run may be required.
• Control board check: If supply voltage is stable and within spec but E04 persists, the internal voltage sensing circuit on the control board may be defective and the board should be replaced.