Set Appliance State:

CH Demand
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

If required, tap reset button to remove fault code / skip self check.
Allow boiler to run for central heating.
Compare the boiler flow temperature (display)
and temperature of the braided bypass hose.
(Hose runs between the two manifolds, behind the gas valve)
Is the bypass hose temperature cooler than the flow temperature
or is bypass hose temperature approximately the same or
greater than the flow temperature, signifying the auto bypass
is passing or open.