Amana Menumaster Err4

What does Amana Menumaster Err4 mean?

Err4 is a service code shown on the display of an Amana Menumaster commercial microwave when the control detects a failed high-voltage (H.V.) board. The control halts the cook cycle and posts Err4 to indicate the board that drives the magnetron circuit has failed; the manual's corrective action is to replace the H.V. board before the oven will heat normally again.

Symptoms

• Display shows Err4 during operation.
• Oven will not heat or start a cook cycle.
• Magnetron does not energize when cooking is selected.
• Code persists across power cycles when the board is faulty.

Common causes

• Failed high-voltage (H.V.) board.
• Failed control or relay components on the H.V. board.
• Fault triggered by an electrical hazard in the high-voltage circuit.

Diagnostic steps

1. 01

   Power down and retest first

   Unplug the oven for one minute, reconnect power, and retest. If the unit operates properly afterward, no service call is required.

2. 02

   Observe high-voltage safety procedures

   Check grounding and discharge the high-voltage capacitor before opening the cabinet; 208/230 VAC is present in the H.V. board and power relay.

3. 03

   Confirm the fault is repeatable

   Run another cook cycle after the reset to confirm Err4 returns rather than being cleared by the power cycle.

4. 04

   Replace the high-voltage board

   The manual lists replacing the H.V. board as the corrective action for Err4. Fit the correct board and verify normal heating.

When to call a professional

Servicing the high-voltage board means working with 208/230 VAC and a charged high-voltage capacitor that must be discharged first. The manual confines these repairs to a trained service technician who follows the eight caution steps. If you are not qualified to service commercial microwave high-voltage circuits, limit yourself to the power-cycle retest and call an authorized Amana Menumaster service agent.