Mike the Boilerman portrait

Mike the Boilerman

Your independent Potterton Suprima repair specialist based near Hungerford, Berkshire. Call or text me on 07866 766364

‍ Fault tracing


‍ The Suprima (not the Suprima HE) is possibly one of the easiest boilers ever to fault-trace. The ignition sequence is simple and short and the multi-colour LED displays fault codes most of which are explained in the documentation. If yours has the original PCB with two separate LEDs one red and one green, it will be different but these are so rare nowadays that I won’t go into detail.


Usually just by watching a Suprima running through the ignition sequence (and failing to light) one can figure out the fault. The sequence is as follows:


1) 230Vac “Call For Heat” voltage arrives on Terminal 4 of the wiring connection block

2) The LED starts alternating amber and green

3) Fan starts

4) Air pressure switch senses fan

5) Sparking at the ignition electrode begins

6) Gas valve opens

7) Gas ignites

8) Electronic flame detection senses flame and sparking stops

9) LED changes to solid green indicating boiler is now running


The most common thing to go wrong is the PCB controling this sequence failing, and incorrectly displaying (usually) flashing or solid red. Any LED pattern or sequence with red in it is a fault report, but most commonly the fault report is false and it is the PCB itself that’s failed. Fortunately plugging in a new or refurbished PCB takes five minutes as a first step and if the boiler now works, the fault was the PCB. If the fault persists then the red light sequence can be looked up in the supplementary manual for the Siemens PCB and the faulty part replaced.




If you'd like me to fix your Suprima, call or text me on 07866 766364.


Mike the Boilerman

Photo of Suprima data label showing red LED fault code and blank spaces where data should have been entered by person replacing the PCB.

Suprima control panel showing red LED fault code

If my pages have been helpful and you’d like to buy me a coffee, click here. Thank you kindly!

Buy me a coffee button

Copyright Michael Bryant 2024

Site first created 12th November 2014

Last updated 17th April 2024


Gas Safe Register 197499.  CIPHE reg no 56207