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Case Study: Thomas Built’s New Stay Warm Feature Decreases Diesel Engine Aftertreatment Maintenance Issues

Thomas Built Buses’ Stay Warm feature is helping school districts reduce the aftertreatment maintenance issues and costs associated with their diesel engine


In early 2017, Thomas Built Buses announced a revolutionary new feature for diesel engines: Diesel Particulate Filter (DPF) Temperature Stabilization, also known as the Stay Warm feature. This new feature optimizes the regenerative parameters of clean-diesel engines, increasing active regeneration and decreasing aftertreatment DPF maintenance issues. What does this mean? Basically, it enhances the aftertreatment system’s ability to regenerate and drastically decreases aftertreatment maintenance issues.

In partnership with Cummins, the Stay Warm feature became standard and factory-programmed on all Cummins engines with a standard exhaust configuration starting April 11, 2017 or later. For customers with an older Cummins engine, model year 2010 or later, Thomas Built dealers can have the engines programmed with this new Stay Warm feature.

A year after its implementation, case studies are showing promising success. While some school districts are seeing up to a 75-percent decrease in aftertreatment-related issues, other school districts now have zero DPF-related maintenance issues.

“We have had phenomenal results with the new Stay Warm feature,” said David Walton, vehicle services coordinator for Prince William County Schools. “We now only have one-off regeneration issues, a dramatic reduction from where we used to be. The minimal issues we have now are not even in the same ballpark as what we’ve experienced in the past.”

Patty Waites of Hamilton Southeastern was one of the first customers to receive the Stay Warm update. “A representative of Cummins came by and changed the parameters of all of our buses. Since the parameter change, we have had zero DPF issues. We just love it.”

Some Thomas Built customers also are adding driver training to further increase the efficiency of their diesel engines.

“Changing the parameters has definitely helped us a lot. We went from six to seven regens a day in the shop to a total of four a week,” said Charlie Turvin, fleet trainer for Loudoun County Public Schools. “But changing parameters is not the only change we made in our shop. We also taught our drivers how to reduce idle time, how to handle a regen and the proper gear to drive in.”

To learn more about the Stay Warm feature and how it can benefit your own fleet, be sure to contact your local dealer.

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