Panasonic Microwave H98 Error — Thermal Fault

What it means

Panasonic microwave H98 error means a thermal overtemperature condition or inverter board fault has been detected.
Unplug the microwave, allow it to cool fully, then attempt a reset.
If H98 returns, the inverter board or a thermal component has failed.

Affected Models

Panasonic Countertop Microwave
Panasonic Over-the-Range Microwave
Panasonic NN Series
Panasonic Inverter Microwave

Common Causes

Overheating of the inverter board from poor ventilation
Failed thermal fuse inside the microwave cabinet
Faulty inverter board
Blocked or failed cooling fan allowing the inverter to overheat
Running the microwave continuously at high power for extended periods

How to Fix It

Unplug the microwave and allow it to cool for 30 minutes.

H98 from overheating will clear once the thermal protection cools.
Do not attempt to restart immediately — give the inverter board and thermal components time to reach room temperature.
Check ventilation clearances.

Ensure the microwave has at least 3 inches (8 cm) of clearance on all ventilation sides.
If it has been running inside a cabinet with the door closed, overheating from restricted airflow is the likely cause of H98.
Check if the microwave was run for an unusually long cycle.

Running a Panasonic inverter microwave at full power for 10+ minutes continuously can cause the inverter to overheat.
Allow it to cool, then test with shorter cooking cycles.
If H98 only appears after very long runs, avoid continuous full-power operation.
Call a technician if H98 returns after cooling.

Persistent H98 after a full cool-down means the thermal fuse has blown, the cooling fan has failed, or the inverter board itself is damaged.
Do not attempt these repairs — all are in the high-voltage circuit.

When to Call a Professional

H98 repairs require access to the inverter board and thermal components inside the high-voltage cabinet.
These repairs must be performed by a qualified technician — the capacitor holds lethal voltage even when unplugged.

Frequently Asked Questions

Panasonic microwave shows H98 every time I use it for more than 5 minutes — what is wrong?

H98 appearing consistently during longer cook cycles suggests the cooling fan has failed or is running slowly, causing the inverter board to overheat quickly. A technician can test the fan and replace it — this is a less expensive repair than a full inverter board replacement.

Is there a difference between H97 and H98 on a Panasonic microwave?

H97 generally indicates a fault detected in the main high-voltage circuit (magnetron or inverter) during operation. H98 is more specifically associated with overtemperature or thermal protection activation. Both require professional repair and both involve the high-voltage circuit.