E08
State
Gas Valve / Gas Control Fault
State tankless water heater shows E08; unit may start then shut down quickly.
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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
Failed gas valve coil, Loose gas valve wiring, Control board not energizing valve, Internal gas valve obstruction
How to Fix / Troubleshooting
Safety: Turn off gas at the manual shutoff and disconnect power. Gas components must be handled by qualified personnel; leaks can cause fire or explosion.
- Visual inspection: Remove the front cover. Locate the gas valve assembly. Check for signs of overheating, corrosion, or physical damage.
- Check wiring: Ensure the gas valve harness is fully seated on both the valve and control board. Look for broken or pinched wires.
- Professional testing: Do not attempt to disassemble the gas valve. A licensed technician should check coil resistance, verify proper voltage from the control board, and perform leak tests. Replace the gas valve assembly if defective.
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Repair Difficulty
Professional Required
5/5
Required Part
Gas Valve Assembly
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