AUSTIN, Texas - Ford's first batch of refurbished Explorers are now back on the streets in Austin after a months-long investigation into potential carbon monoxide poisoning.

To date, Austin Police Department has returned 44 of its more than 400 Utility Police Interceptor vehicles to the road. Those are Ford Explorers that are modified by the manufacturer to meet the pursuit requirements for law enforcement agencies.

"The top of our priority list is the safety of our officers," Asst. Chief Justin Newsom said. "If we don't have that, then we don't have the safety of citizens. We have to ensure that when we put officers back to work, that we're 100 percent comfortable with the fixes from Ford and our own internal fleet department."

Austin Police Department pulled all of the SUVs out of service after about two dozen officers said the carbon monoxide from the SUVs made them sick. Two of the officers remain home recovering from their injuries; three others are on light duty.

"Hopefully they make a full recovery," Newsom said. "Hopefully they can get back to work, doing what they love. Hopefully there are no long-term effects from this."

Ford Motor Co. agreed to cover the cost of all repairs to the vehicles, whether they were caused by manufacturer defect or aftermarket modifications.

RELATED | Ford begins repairs on Austin Police Department's Explorers

Jim Teague with Austin Fleet Services said Ford replaced the seal for the rear hatch. It also redesigned the brackets for the hatch, so it would have a tighter seal. Teague said the manufacturer also replaced the exhaust system with tailpipes that point downward instead of to the rear in an effort to reduce turbidity.

Upon receiving the first batch of SUVs in September, the city put every vehicle through a detailed inspection and rigorous road test.

"Taking the vehicle out in an hour-long test drive from a fleet perspective by putting it through hard braking and acceleration," said Fleet Services Officer Jennifer Walls.

She said all vehicles have passed the city's tests. The remaining SUVs are expected to be back in service within the next four months. In the meantime, officers will continue to be paired up in a fleet made up largely of Ford Crown Victorias that were slated for auction.