Honda NRX1800 2004 Owner's Manual page 38

If all ignition keys are lost, the PGM-FI
unit/ignition control module must be
replaced. If you have just one key left, we
recommend that you have it copied to
ensure that a backup is available.
These ignition keys contain electronic
circuits that are activated by the
immobilizer system (HISS). They will not
work to start the engine or release the
steering lock if the circuits are damaged.
Do not drop the keys or set heavy
objects on them.
Do not grind, drill or in any way alter
the original shape of the keys.
Keep the keys away from magnetic
objects.
Controls & Features
Instruments & Controls
29