Leaking Worcester 24i Junior boiler?

Hi, I have a 3 year old Worcester 24i Junior boiler in my caravan (LPG) that has suffered during the recent cold spell. The CH is working fine but, unfortunately, when I turned the stop tap on water started leaking down the water inlet pipe, just underneath where the water flow turbine is. It sounds like I know what I am talking about but I have the instruction manual open in front of me. Is it likely the flow turbine is the culprit and needs replacing or is there anything else that maybe the cause. I have not taken the boiler cover off yet as I had no tools with me at the time. Any help or guidance would be greatly appreciated.