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Rinnai gas heater code 53: Spark sensor fault

Gas heater, Australia

The spark (ignition) sensor is faulty.

This needs a licensed gasfitter. There is nothing safe to check yourself. Leave the covers on and book a professional.

This involves the gas supply or burner. Only a licensed technician should open the unit or work on gas parts.

What causes it

  1. A faulty spark sensor. A service call is required.

    Book a licensed gasfitter

How to read this code on your unit

Booking a licensed gasfitter

Book a licensed gasfitterlicensed gasfitter

  1. Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
  2. Note the code, how often it appears, and the model and serial numbers from the rating label.
  3. Book a licensed gasfitter and give them those details.

Models that show this code

6 models in 2 ranges
RangeModels
Energysaver FDT commercial flued gas heaterRHFE-559FTSN (Energysaver 559FDT), RHFE-1005FTSN (Energysaver 1005FDT)
Energysaver FT flued gas heaterRHFE-309FT3 (Energysaver 309FT), RHFE-559FT3 (Energysaver 559FT), RHFE-561FT3 (Energysaver 561FT), RHFE-1005FT3 (Energysaver 1005FT)

Where this comes from

Checked against the manufacturer's manual on 9 October 2026.

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Other Rinnai gas heater codes

Code Meaning What you can do
32 Room temperature sensor fault Safe checks first, then a pro
33 Overheat temperature sensor fault Safe checks first, then a pro
34 Overheat temperature sensor fault Safe checks first, then a pro
35 Overheat temperature sensor fault Safe checks first, then a pro
40 Sensor tube failure Call a pro
49 Sensor breakdown Safe checks first, then a pro
61 Combustion fan fault Safe checks first, then a pro
62 Convection fan fault Safe checks first, then a pro
70 On/Off switch fault Call a pro
71 Gas solenoid fault Call a pro
72 Flame detection circuit fault Call a pro
73 Communication error Safe checks first, then a pro