F1 error C49 = PAIR control solenoid valve Now what?

[Brockett]

The bike has not been used for a longish time.

The engine started but with F1 light on.
Put into dealer check mode and C49 was indicated on the dash.
"PAIR control solenoid valve".

Anyone have a hint or three as to what I am to look for / check?

Battery shows 12.45 volts across the terminals with ignition switched off.

[Brockett]

I just found it in the on line manual so I know where to start. Possible maybe I dislodged something when I changed the air filter.
Oh! damn I have take all that stuff off again to check it out.

[Hondaman]

I can't see there being any kind of sensor to check/confirm operation so probably the connector has not been fitted properly

[TLPower]

Typical bloody train driver, always blaming the signals.......

[Brockett]

Managed to get some garage time today  and so I stripped off the bodywork,tank and lifted the air cleaner to find I had not connected the sensor 

All back together and starts and runs fine.  Only a road test to go before it is declared fit and well after all the work I have done on it.