Caterpillar also allegedly failed to comply with emission control reporting and engine-labeling requirements. Caterpillar will pay a $2.55 million penalty, continue a recall of noncompliant engines and reduce excess emissions.

“This settlement demonstrates our commitment to enforcing the Clean Air Act’s requirement that engine manufacturers take steps to ensure engines are equipped with emissions controls,” said Ignacia S. Moreno, assistant attorney general for the DoJ Environment and Natural Resources Division. “Caterpillar will pay a substantial civil penalty for shipping engines that did not comply with these Clean Air Act requirements, and under this settlement, it must continue its recall and correction of engines that do not have correctly configured emissions controls.”

The Clean Air Act requires the use of certified after-treatment devices (ATDs) that control engine exhaust emissions once the emissions have exited the engine and entered the exhaust system. Typical ATDs include catalytic converters and diesel particulate filters. Correct fuel injector and fuel map settings are also crucial for proper engine emission control. Caterpillar allegedly shipped more than 590,000 engines to vehicle assemblers without the correct ATDs and with improperly configured fuel injector and map settings. In some cases, the mis-configured engines were incorporated into vehicles which resulted in excess emissions of NOx and particulate matter into the environment.