The trouble with generic code readers is that they don't always give you the full story, particularly for any non-engine related fault codes that crop up. The generic code will probably relate to standard automatic gearboxes, where I'm guessing yours is an I-Shift gearbox?
A quick google reveals that P0974 seems to appears for other faults, not just solenoid circuits. The full code for Honda is
P0974 Open in Shift Solenoid Valve A Circuit
...which indicates open circuit, or in other words, something is disconnected. It might be worth checking that all connectors onto the gearbox are secured, make sure they are all fully home, and that no wiring or loom is damaged.