Firstly, please check that the probe has not become blocked by dirt or grease. Switch off the GasCheck and remove the probe assembly using the box spanner (included). Using a small cleaning wire, push the wire through the probe from the connection side through to the inlet. Alternatively, use clean, dry compressed air to blow through the probe from the connection side through to the inlet.
If problems persist, this is an indication that there may be a problem with the fan assembly. Please contact firstname.lastname@example.org for further information.