DETROIT (AP) — U.S. auto safety regulators will not seek a recall after a seven-year investigation into complaints alleging that Dodge and Ram vehicles can roll away after being shifted into park.

The problem was similar to one that was blamed in the death of Star Trek actor Anton Yelchin, although the company was in the process of recalling his 2015 Jeep Grand Cherokee to address the issue.

The investigation, opened in December of 2016, covered almost 1.3 million Ram 1500 pickup trucks from the 2013 to 2017 model years, as well as Dodge Durango SUVs from 2014 through 2017.

At issue were electronic dial-like rotary gear selector knobs that were new at the time and different from previous mechanical shifters that used a lever to select gears. The knobs are turned to the left or right and have detents that click into gear.

The National Highway Traffic Safety Administration says in documents posted on its website Monday that it and Stellantis, formerly Fiat Chrysler, had received nearly 1,500 complaints that the vehicles would roll after drivers put them in park.

But the agency said it did not find evidence that a design or manufacturing defect caused the rollaway incidents. Plus, Fiat Chrysler did a “customer satisfaction campaign” to update software so the vehicles automatically shift into park if the driver's door is opened.

The agency said it monitored vehicles that got the update and found that the service campaign was “effective in reducing the frequency of vehicle rollaway incidents in the subject vehicles.”

Investigators also analyzed reports that the vehicles rolled away even after the software update, but did not find an “actionable defect” that caused the problems. The agency also said that after the service campaign, customer complaints significantly decreased.

“Given the absence of an identified safety defect based on available information and FCA’s customer satisfaction campaign which addresses the failure mode, further action is not warranted at this time,” the agency wrote.

In a statement, Stellantis said it agrees with NHTSA’s findings and is “pleased that our update appears to have resonated with customers.”

Yelchin, 27, known for playing Chekov in the Star Trek film series, died in June of 2016 after his Jeep pinned him against a mailbox pillar and security fence at his home in Los Angeles.

His Grand Cherokee SUV was among a group of vehicles recalled because of complaints from drivers who had trouble telling if they put the console-mounted shift levers in park after stopping. Many reported that the vehicles rolled off after the driver exited.

The Grand Cherokee shift levers like Yelchin’s had to be pushed forward or backward to change gears, confusing many drivers. In the recall, Fiat Chrysler changed the software so the vehicles automatically shift into park if the driver’s door is opened.