A CO sensor module includes a housing, a CO sensor, and a module battery. The housing has a first portion that is configured to be removably inserted into a compartment of a generator and a second portion that is configured to be positioned outside of the compartment. The CO sensor is positioned within the first portion of the housing and is configured to detect concentrations of CO. The module battery is positioned within the housing and is configured to power the CO sensor module. The second portion of the housing includes a mounting ring that is configured to abut a control panel of the generator in an installed position.