Bosch induction cooktop displays E021 on one or more zones; those zones do not heat.

Safety first: Disconnect power at the breaker. High-voltage components inside the power module can retain charge; only qualified persons should test live circuits.

• Reset the unit: Turn off power for 10 minutes, then restore. If E021 reappears on the same zone, the fault is likely hardware-related.
• Check cookware and size: Confirm you are using induction-compatible cookware of appropriate size. While this usually causes pan detection issues, it is worth ruling out simple causes.
• Inspect coil connections (advanced): Remove the glass top and inspect the wiring from the affected induction coil to the power module. Look for burned connectors or broken wires.
• Replace coil or power module: If the coil is physically damaged or open, replace the induction coil. If the coil tests good but the zone still shows E021, replace the power module for that zone.