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Rinnai Error Code Block 05: Outdoor sensor not connected (Boiler)

Updated · by Aurora Star Tech Inc.

Rinnai error code Block 05 on a boiler means: Outdoor sensor not connected. It is also called Rinnai diagnostic code Block 05.

Low severityBoilerE-Combi (E50CRN · E75CRN/E75CRP · E110CRN/E110CRP)

Homeowner? What Rinnai code Block 05 means for you

Usually minor Your boiler is reporting: Outdoor sensor not connected. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.

Safe things you can check yourself

  • Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
  • Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
  • Look at the pressure gauge on the boiler. If it reads much lower than usual or near zero, or water is leaking, call a technician.
  • Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
  • Check that the boiler gas valve is open (handle in line with the pipe).
  • Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does Rinnai error code Block 05 mean?

Temporary block: the control sees an open outdoor-sensor circuit (sensor missing or wire broken).

Applies to: E50CRN; E75CRN; E75CRP; E110CRN; E110CRP

Common causes of Rinnai code Block 05

  • Outdoor sensor not connected
  • Wiring fault on terminals 18/19
  • Failed outdoor sensor
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

Other Rinnai Boiler codes

CodeMeaning
7630-10V external control input over-voltage
831Indirect tank call running too long
890Freeze condition detected
999PC Board / software mismatch
A XXDe-aeration running
Block 01External safety contact open
Block 60Wrong minimum/maximum power parameter
Block 67Supply/return sensor difference with burner off
Block 85No water flow detected
COdEAccess code entry
CopyFactory settings restored
E00Poor flame formation (flame sensed with burner off)

All Rinnai Boiler error codes →

Rinnai code Block 05: homeowner questions

What does Rinnai code Block 05 mean?

Outdoor sensor not connected. Temporary block: the control sees an open outdoor-sensor circuit (sensor missing or wire broken).

Is it safe to keep using my boiler with code Block 05?

Usually yes. Code Block 05 is normally minor, but if it keeps coming back have it checked.

Can I reset Rinnai code Block 05 myself?

You can try one reset (power off for 30 seconds, then on). If Rinnai code Block 05 comes back, the cause is still there and a licensed technician should check it.

Who can fix Rinnai code Block 05 near me?

Aurora Star Tech Inc. repairs Rinnai boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Boiler Not Heating: What to Check

Troubleshooting guides

Source: Rinnai E-Combi Series Installation & Servicing Instructions (8U516009 V0116), p.71-72 (15.1, 15.2). Written in our own words as a summary; always check the original manual.

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

Emergency Boiler Repair

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