This is not a fault code. Hense why you cannot find it in the service and installation book. This is a special feature of some Worcester CDi boilers .It is actually a reminder that the boiler requires a service based on burner hours.
You have probably just done some maintenance work on a Worcester Bosch CDi, Ci, Si boiler, Greenstar or Junior Boiler (System, conventional and combination boilers affected) or associated heating system. Wondering what has happened to the boiler, answer nothing.
Our boiler is now seriously faulty - it cuts out pretty much every day, sometimes more than once. Sometimes it shows the F22 error message; sometimes it simply doesn't fire up even though the temperature is showing around 30 degrees.
On the other hand, o...