H97 and H98 on a Panasonic microwave both point to a problem with the magnetron or the high-voltage inverter circuit that powers it, per Panasonic’s own support documentation. U-series codes are generally simpler — U14, for example, just means the water tank is empty on Combination Steam models — while codes starting with H typically need a technician.
The documented code list
| Code / message | What Panasonic’s support pages say it means |
|---|---|
| H95 | A problem with the inverter circuit, which controls power output to the magnetron |
| H97 or H98 | A problem with the magnetron itself, the high-voltage circuitry, or related components |
| H99 | A general error the internal monitoring system detected with no specific code assigned |
| E01 | Requires immediate service — contact an Authorized Panasonic Service Center |
| E05 / E06 / E08 | Requires service — contact an Authorized Panasonic Service Center |
| U14 | The water tank is empty (Combination Steam models) — refill and reposition it |
| U50 | Oven is overheated — allow it to cool down |
| U90 | The drain water function has been used 3 times consecutively |
| COOLING | The fan is running to cool internal components — normal operation, not a fault |
| DEMO MODE / D | The unit is in demonstration mode and will not heat food |
| HOT or HOT INSIDE WAIT | Oven temperature is too high from previous use — the cavity is overheated |
H-series codes: system-level faults
H95, H97, H98 and H99 all relate to internal system monitoring rather than something a user setting or accessory can cause. H95 points specifically at the inverter circuit — the component that regulates power delivered to the magnetron — while H97/H98 point at the magnetron itself or the high-voltage circuitry feeding it. H99 is Panasonic’s catch-all for an internal fault that does not match a more specific code. All of these require a technician: Panasonic’s own guidance is clear that microwaves contain high-voltage components that stay dangerous even after being unplugged, and this is not a DIY-safe repair area.
U-series codes: usually user-resolvable
- U14: empty water tank
Applies to Combination Steam models — refill the tank and make sure it is fully and correctly repositioned in the oven.
- U50: overheated
Let the unit sit and cool down fully before running it again — this is a thermal protection response, not a hardware fault.
- U90: drain function used repeatedly
Appears after the drain water function has run 3 times in a row — check your model’s manual for the specific next step it expects.
Messages that are not actually errors
COOLING, DEMO MODE (or a plain “D”), and HOT/HOT INSIDE WAIT are all normal operational messages rather than faults. COOLING disappears on its own once the cooling fan finishes its cycle. DEMO MODE means the unit is intentionally running in a no-heat demonstration state (common on floor/display units, and occasionally triggered accidentally) — check your manual for the specific key combination to exit it. HOT INSIDE WAIT simply means the cavity is still hot from recent use.
When to call for service
Panasonic’s own documentation directs any H-series code, along with E01, E05, E06 and E08, to an Authorized Panasonic Service Center rather than DIY troubleshooting — these all involve the high-voltage system that generates microwave energy, which is not safe to open up without proper training and discharge procedures.
