E18
Ruud Gas Valve Control Fault

Boiler displays E18; may be associated with gas valve operation

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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

Defective gas valve coil, loose gas valve connector, incorrect gas valve wiring, failed gas valve driver on control board

How to Fix / Troubleshooting

Safety first: Turn off power and shut off gas at the manual shutoff valve. Do not attempt gas valve replacement without proper licensing.

  • Inspect wiring: Check the gas valve connector for tightness and signs of heat damage. Reseat the plug.
  • Check gas shutoff: Confirm the manual gas valve is fully open and that there are no additional shutoffs closed.
  • Reset and test: Restore power and attempt a call for heat. If E18 returns immediately, the gas valve or control board may be defective.
  • Professional testing required: Gas valve coil resistance and control output voltage should be tested by a qualified technician. If the valve is replaced, leak testing and combustion setup are mandatory.
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Repair Difficulty

Professional Required 5/5

Required Part

Gas Valve Assembly
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