F9 on boiler, fires up after reset only

[JWBrooks]

I have a Glow-Worm Ultrapower sxi. I am used to sorting out an F9 by topping up to about 1.5 bar, then the boiler fires up. However twice now I have found an F9 and after pressing the reset button the boiler fires up without any top up and the indicated pressure is >2bar. Is it possible that there is too much pressure in the system and the boiler will display F9 to indicate that as well as too little?

 

[Gasmk1]

Could be your pressure sensor is faulty you may need an engineer out to sort

 

[Aquarius]

Can be a few things, might need someone in. Might be equivalent of Vaillant f75.

 

[JWBrooks]

Pressure sensor changed, problem cured. Thanks guys.