WASHINGTON (Reuters) -Truck engine maker Cummins Inc has agreed in principle to pay a $1.675 billion fine for installing devices on hundreds of thousands of engines to allow them to emit excess pollution, the largest-ever civil penalty for a Clean Air Act violation, the U.S. Justice Department said on Friday. The Department said Cummins allegedly installed so-called "defeat devices" to bypass or disable emissions controls such as emission sensors and onboard computers. The department said Cummins used defeat devices on 630,000 2013 to 2019 RAM 2500 and 3500 pickup truck engines and undisclosed auxiliary emission control devices on 330,000 2019 to 2023 RAM 2500 and 3500 pickup truck engines to cheat emissions control requirements.