As school districts prepare for the fall semester, maintenance crews face a race against time to get buses road-ready. One of the top challenges: avoiding emissions component failures that can sideline vehicles and strain budgets.
Preventive maintenance and backup plans – including reliable service shops and access to rental buses – are key to keeping fleets rolling. The experts at Master’s Transportation, which operates 12 locations nationwide and recently opened a 32,000-square-foot parts and service facility, share their strategies for avoiding downtime and protecting budgets.
Bus & Motorcoach News spoke with Brian Schamma, Vice President of Sales and Leasing at Master’s Transportation, and Jimmy Bink, Vice President of the Parts and Service Division, about the issues fleets face and how to get ahead of them.
BMN: What are the most common emissions system failures school bus fleets encounter at the start of the school year, and how can they be prevented?
Schamma: DEF (diesel exhaust fluid) head and sensor failures are the top culprits, especially after buses sit idle over the summer. Regular operation keeps systems at proper temperature and fluids circulating. We recommend starting buses weekly and driving them long enough to reach full operating temperature. That simple step can greatly reduce the risk of emissions failures when the school year starts.
Bink: Tracking DEF usage can also help spot trouble early. If consumption spikes, there may be inefficiencies in the system. And drivers should always let regeneration cycles finish before shutting off the engine. Cutting them short leads to soot buildup, damaged sensors, and reduced efficiency.
BMN: Which components should maintenance teams prioritize during preseason inspections?
Bink: Address warning lights immediately—waiting only makes the problem worse and more expensive. Update the engine control module with the latest manufacturer software to prevent known issues. Also, clean the DEF filter annually to remove soot and ash buildup. That keeps the emissions system working efficiently and helps avoid mid-semester derates.
BMN: How do emissions-related failures affect compliance, safety and budgets?
Schamma: Safety is the biggest concern. If a bus derates on a route or highway with students on board, the driver’s ability to navigate traffic is compromised. Operationally, failures cause delays, route disruptions, and overtime costs. Financially, districts with tight budgets feel the pinch from repair bills, emergency transport arrangements, and even compliance penalties.
BMN: The EPA recently announced changes to derate rules. How will this impact school bus operations?
Bink: This is a game-changer for school transportation. The new EPA guidance creates a phased approach that gives operators much more time before severe speed restrictions. Instead of facing drastic derates within just four hours of a DEF system fault, buses now have no torque reduction for the first 650 miles, or approximately 10 hours. This means buses won’t suddenly slow to unsafe speeds during routes if a DEF sensor fails.
Schamma: These new regulations mark a milestone in addressing a problem that has long been a huge burden on the bus industry. While DEF systems still should be fixed for optimal performance, this eliminates the safety issue associated with the derating of school buses. School districts can now focus on proper repairs rather than emergency responses. With the extended timeline—which eventually progresses to a 15% torque reduction, then 30%, and only limits speed to 25 mph after about 160 hours—maintenance teams can schedule service during off-hours instead of pulling buses mid-route. This dramatically improves student safety while reducing costly service disruptions and emergency rental needs.
BMN: What steps can fleet managers take now to ensure reliable service, parts, and rentals when issues arise?
Bink: Build relationships with service providers before you need them. Master’s Transportation has nine service centers equipped with advanced diagnostics for emissions systems, plus a centralized parts department with thousands of components in stock. We also offer emergency rentals with nationwide delivery so that districts can maintain schedules even during major repairs. Preventive maintenance agreements give fleets priority for service and parts during peak demand.
BMN: How is Master’s Transportation investing to support fleets?
Bink: We use advanced software to perform ECM updates and partner with specialists for cleaning and testing removed filters, which extends component life. For replacements, we source directly from OEMs and trusted aftermarket vendors to ensure reliability. Our technicians are in the process of being trained or are already trained on implementing the new EPA-approved software changes that prevent abrupt derates, helping school districts transition smoothly to the new standards. Our goal is to match fleets with the most dependable parts and repair solutions for their specific needs and operating conditions.
