Set Appliance State:
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Measurement:
Disconnect the Red wire and Black wire (1) from the Gas Valve Stage 2 Solenoid (solenoid 3), and measure the resistance across the Solenoid.
The Solenoid Resistance should be:
approximately 125 ohms for SIT valve; and
approximately 120 ohms for Honeywell valve.
Reconnect wires after test.
The Solenoid Resistance should be:
approximately 125 ohms for SIT valve; and
approximately 120 ohms for Honeywell valve.
Reconnect wires after test.
Isolate as per TOPs P4
and refit as necessary