City officials said the cause is under investigation.
EMS helped the four people who were exposed to the CO, and one person went to the hospital.
Besides paying the fine, CenterPoint Energy Indiana North pledged to make changes to its operations and conduct training with local first responders in Clark and Floyd counties.
Doctors said children and elderly are most vulnerable to extreme temperatures and kids are more likely to lose heat.
The National Fire Protection Association says the risk of dying in reported home structure fires is 55 percent lower in homes with working smoke detectors.
The mistake led to more than 100 calls of carbon monoxide issues in Clarksville, Jeffersonville and New Albany around Christmas Eve, hospitalizing at least four people.
State Rep. Rita Fleming confirmed that CenterPoint Energy had hired Minnesota-based Standby Systems.
The Clarksville Fire Department started getting so many calls that an emergency command center was set up.
Clarksville is still waiting the results of an investigation after a carbon monoxide scare on Christmas Eve.
Firefighters in Clarksville have responded to more than 100 reports of gas or carbon monoxide leaks over the past three days.