Volvo says its engines are now available with a new feature that lowers NOx emissions to levels to meet California’s very stringent low-emissions truck idling requirements.

Volvo’s D11, D13 and D16 engines can now be equipped with an optional Low NOx Idle (LNI) feature, which allows customers to idle indefinitely in California and still comply with emissions standards. Engines that aren’t equipped with the option must not idle in the state for any longer than five minutes. The restriction is also in place in Pennsylvania and New Jersey and other states are also looking at adopting the rule.

With the option, Volvo’s engines will emit less than 30 grams/hr of NOx while idling, the company says.

The option allows the Volvo engines to idle at a low 700 RPM and it also employs a low level of exhaust gas recirculation, which reduces the fuel consumed at idle, lowering NOx emissions. The company says the option also provides a faster engine warm-up so the truck can be driven sooner after a cold start.

The Cummins ISX, which is available in some Volvo truck models, also meets the California NOx limits. So all engines built after January 1, 2008, for Volvo trucks are certified to meet the NOx idle limits. Volvo trucks with these engines are now in production.