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Riello RDB 2.2 Burner Control (MO 535 - MPF)

Riello RDB 2.2 Burner Control (MO 535 - MPF) Orange steady on: Reset button: steady orange

The burner control locks out due to a mains supply frequency error, stopping the heating system.

Code
Orange steady on
Name
Reset button: steady orange
Controller
Riello RDB 2.2 Burner Control (MO 535 - MPF)
Type
General fault
What it does
Warning: the equipment keeps running and flags a problem
Risk
GREEN In your wheelhouse
Reset
Clears on its own when the condition goes away
Source
The manufacturer's manual (subscribers see which manual and page)

Updated July 23, 2026

How to fix it

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  • What to do next, in plain words
  • Which manufacturer manual it comes from, linked
  • The 3 common causes listed for this code
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Questions about this code

What does Riello RDB 2.2 Burner Control (MO 535 - MPF) Orange steady on mean?

The burner control locks out due to a mains supply frequency error, stopping the heating system.

Is Riello RDB 2.2 Burner Control (MO 535 - MPF) Orange steady on dangerous?

It is graded green: in a working tech's wheelhouse with standard tools and low risk.

How do I fix Riello RDB 2.2 Burner Control (MO 535 - MPF) Orange steady on?

The manual's fix and the step by step check for this code are in WERCS Diagnose, plans from $49 a month. For help right now, WERCS answers 24/7 at (877) 489-3727.

Other Riello RDB 2.2 Burner Control (MO 535 - MPF) codes

Red steady on · Reset button: steady redRed blinking (0.5s/0.5s) · Reset button: red blinkingRed fast blinking (0.2s/0.2s) · Reset button: red fast blinkingGreen + red blinking (0.5s/0.5s) · Reset button: green and red blinkingOrange + green blinking (0.5s/0.5s) · Reset button: orange and green blinkingOrange + green fast blinking (0.2s/0.2s) · Reset button: orange and green fast blinRed + green inverted flashing (2.5s/0.5s) · Reset button: red and green inverted flaRed + orange inverted flashing (2.5s/0.5s) · Reset button: red and orange inverted fl

All 9 Riello RDB 2.2 Burner Control (MO 535 - MPF) codes · Every fault code