Do you remember Dieselgate? Well, this time it is Cummins in the legal crosshairs, and although it denies wrongdoing, the engine maker has agreed to pay a $1.675 billion penalty for diesel engines in Ram pickups fitted with “defeat devices” that allowed excessive nitrogen oxide (NOx) levels in everyday use, federal officials say.

Cummins will also pay another $325 million towards remedying the violations and also recall more than 630,000 Ram 2500 and 3500 trucks, according to the settlement, published by the EPA on Wednesday. The recall involves rigs fitted with the long-serving 6.7L Cummins engine produced between 2013 and 2019. The penalty will be the largest ever levied for a violation of the Clean Air Act, being higher than the $1.45 billion that Volkswagen paid for Dieselgate.

The EPA says it originally discovered that diesel-powered Ram trucks were performing differently in real-world and laboratory conditions during post-Dieselgate testing. As with Volkswagen, this is alleged to have been done using defeat devices, which detected when a truck was undergoing the standard emissions testing cycle and would work to reduce emissions accordingly. Much higher levels of NOx emissions were then emitted during normal driving. As all Cummins 6.7L Ram trucks from the 2013 model year onwards have been fitted with Diesel Exhaust Fluid injection systems – explicitly to reduce NOx – it looks as if this was operating at a lower level.

Although all of the affected trucks were sold by Ram, Cummins is responsible for the recall program. The official statement says this will only involve a software update installed at Ram dealers, but additionally, Cummins will offer a new extended warranty for the emissions control systems of updated trucks. As per the settlement, the engine maker must update at least 85 percent of the 2013-2019 trucks with the identified defeat device within three years.