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R
5 flashes
Moderate
Rheem · HVAC Systems & Water Heaters
Ignition Fault
Quick Answer
Error code 5 flashes on your Rheem HVAC Systems & Water Heaters means: Ignition Fault. This is usually fixable — see the step-by-step guide below.
Likely Causes
  1. Hot surface igniter failed or cracked
  2. Gas supply off or insufficient gas pressure at the manifold
  3. Gas valve not opening when commanded by the control board
  4. Dirty burners preventing proper gas ignition
  5. Control board ignition timing circuit failure
How to Fix It
1
Verify the gas supply valve is open and other gas appliances in the home function normally
2
Remove the igniter and inspect for cracks, white spots, or other visible damage
3
Measure igniter resistance with a multimeter (silicon nitride: 40-200 ohms)
4
Verify 120VAC is sent to the igniter during the ignition trial period
5
Check gas manifold pressure with a manometer (3.5 in WC for natural gas, 10.0 in WC for LP)
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Hot surface igniter
Gas valve
Igniter gasket
Related Error Codes
1 flash2 flashes3 flashes4 flashes6 flashes
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