H21
Panasonic
Gas Solenoid Valve Error
Panasonic water heater shows H21; unit may not ignite or may shut down with gas‑related issues.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Open or shorted gas valve coil, Loose gas valve connector, Defective main control PCB output, Internal gas valve mechanical failure
How to Fix / Troubleshooting
Gas safety: Do not attempt to open or repair the gas valve body yourself. Only licensed technicians should replace gas valves.
- 1. Reset unit: Turn OFF power for several minutes, then restore and test.
- 2. Inspect gas valve wiring (qualified persons):
- Remove the front cover.
- Locate the gas valve and its electrical connector.
- Ensure the connector is fully seated and not heat‑damaged.
- 3. Check for signs of overheating:
- Discoloration or melting near the valve coil suggests failure; the valve must be replaced.
- 4. If H21 persists: Have an authorized Panasonic technician test the gas valve coil resistance and PCB output, and replace the gas valve assembly if necessary.
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Repair Difficulty
Professional Required
5/5
Required Part
Gas Control Valve Assembly
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