Etna induction cooktop shows E4 on one or more zones, often immediately when turned on.

Safety: Disconnect power at the breaker. High-voltage components inside can retain charge; do not touch capacitors.

• Visual inspection: Remove the cooktop from the worktop and open the bottom cover. Inspect the induction coil for burn marks, cracks, or detached windings.
• Check wiring: Ensure the coil leads are firmly connected to the power module and that the harness is not burnt or pinched.
• Test continuity: With a multimeter, measure resistance of the coil; an open circuit or very low resistance indicates a faulty coil.
• Inspect power module: Look for burnt components, cracked IGBTs, or darkened PCB areas. If present, the entire module should be replaced.
• Do not bypass safety: Never attempt to bridge or bypass the coil or power components; replace the defective parts.