Display shows E3 and charging stops or will not start.

Safety first: Turn OFF the charger breaker before opening any electrical panels. Only a qualified person should work inside the service panel.

• Measure supply voltage: Have an electrician measure the line-to-line (for 240 V) or line-to-neutral (for 120 V models) voltage at the charger input terminals. Compare to the nameplate rating on the Schumacher EV charger.
• Check for loose connections: With power OFF, inspect the lugs at the charger input and at the breaker for tightness and signs of overheating (discoloration, melted insulation). Tighten to manufacturer torque specs if loose.
• Inspect surge/EMI board: If accessible per the service manual, visually inspect the internal surge protection/EMI filter board for burn marks or bulged components. If damaged, the board must be replaced as an assembly.
• Retry after stabilization: If the utility voltage was temporarily high (e.g., after an outage), wait 15–30 minutes and try again.
• If E3 persists with normal voltage: The overvoltage sensing circuit on the main control board or surge board may be defective. Contact Schumacher support or an EVSE technician for board replacement.