Viessmann Vitodens 050 F2 fault after replacing radiator

[Jonahea]

System worked fine before, in fact it’s only 18 months old and was just serviced. But I just took off a radiator to redecorate and after putting it back on and filling it up I have at F2 fault.

When turning the hot water on, the temperature goes up past 100 and then the F2 appears. So it appears it’s overheating.

-I have tried resetting
-I have tried bleeding the boiler and repressurising
-Radiators all appear full and properly bleed
-Pressure is 1-1.2ish
-Central heating works fine

Any clues? Do I need to get a gas man out?

 

[CBW]

Probably air locked, might just need venting still

 

[Jonahea]

What’s the best way to do this?

Just keep bleeding the rads and topping up or a different way?

And thanks!

 

[Jonahea]

FYI - It needs an Veissmann engineer.
Debris in the system. A quick flush and all good to go again. No replacement parts were required.