Abstract: A system for controlling engine operation responsive to engine emitted CO presence in a closed space includes a CO sensor carried in a control unit in the vehicle or in the space. Other control units can be used and are associated with a space closure door and a space fan unit. When the sensor unit detects an unacceptable CO level in the space signals including discrete RF signals are generated to effect engine shutdown and to open a space closure door as well as operate a space ventilation fan until a safe CO level in the space is produced at which point second signals are generated to shut the closure door, turn off the ventilation fan and optionally re-enable engine operation.