We have a '96 370 Voyager with hard wired Co2 detectors, which I replaced last year with Fireboy-Xinex CMD6 units. My question is; Are hard wired Co2 detectors connected in some way to the audible helm alarms? I thought the alarms on the Co2 units were self emitting and that wiring was only for power.

The reason I ask? Today after coming off plane with a tail wind, the helm alarms went off, but there was no loss of oil pressure or overheating and both engines were running fine. After 3-4 minutes, the helm alarm stopped. Once tied up and engines were off, I checked engine room and felt inboard elbows, manifolds and transmission housings and all felt normal but there was a faint smell of exhaust in the salon area where one of the sensors is mounted.

If the Co2 sensors are not connected to the helm alarm, any ideas as to why the alarm would go off?