E20
Oso Lockout Due to Repeated Overheat or Sensor Errors

Oso water heater shows E20; unit may lock out after repeated faults.

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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

Unresolved underlying sensor or overheat issues, Control board safety lockout logic, User repeatedly resetting without fixing cause

How to Fix / Troubleshooting

Safety first: Do not repeatedly reset a locked‑out heater without identifying the root cause. Isolate power before inspection.

  • Review history: Check the display or manual for which primary error (E02, E03, etc.) triggered the lockout.
  • Fix root cause: Address the underlying overheat, sensor, or wiring issue as per the relevant error code procedure.
  • Manual reset: After repair, perform the manufacturer’s lockout reset procedure (often holding specific buttons or cycling power for a set time).
  • Monitor operation: Observe at least one full heat cycle to ensure the fault does not recur.
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Repair Difficulty

Medium 3/5

Required Part

Oso control PCB (safety lockout function)
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