Truck maintenance schedule: what to service and when
Updated · Reviewed by Israel Margulies, founder and CEO of High Point GPS
A truck maintenance schedule has four layers: the driver’s daily inspection, a light A service, a fuller B service, and a C service that usually lines up with the annual inspection required by 49 CFR 396.17. Shops set the A, B and C intervals from the engine and chassis makers’ manuals, by miles, engine hours or months, whichever comes first. Federal rules then set the minimum for inspections and records on top.
How A, B and C truck PM services work
A, B and C are shop conventions, not federal categories, and their contents differ from fleet to fleet. In a common setup the A service is the short one, done at each oil change or a set mileage. The B service includes everything in the A plus more inspection and filter work. The C service is the longest and often includes the annual periodic inspection. Each level contains the one below it, so a technician doing a B never skips the A items.
Set the interval for each level from the manuals for the engine, transmission and axles, adjusted for your duty cycle. A hypothetical regional fleet whose engine maker allows a long oil drain interval might do an A at every drain, a B at every second drain and a C once a year. A vocational truck that idles for hours at job sites may need intervals by engine hours instead of miles, because the engine wears while the odometer stands still.
Daily: the driver vehicle inspection report
Under 49 CFR 396.11, drivers prepare a report at the end of each day’s work on each vehicle operated. The report covers at least the service brakes including trailer brake connections, parking brake, steering mechanism, lighting devices and reflectors, tires, horn, windshield wipers, rear vision mirrors, coupling devices, wheels and rims, and emergency equipment. A driver who finds no defect, and has none reported to them, does not have to prepare a report; since a 2020 FMCSA rule that exemption covers passenger carriers as well as property carriers.
When a report lists a defect that would affect safe operation, the carrier repairs it before the vehicle runs again and certifies on the report that it was repaired or that repair is unnecessary. Carriers keep the report and the certifications for three months. Under 49 CFR 396.13, the next driver reviews the last report when one was prepared, and signs it to acknowledge that the listed defects were certified as repaired; a report is only prepared when defects were noted. Single-vehicle carriers are exempt from 396.11, though a daily walk-around is still good practice.
What goes in an A service
Keep the A short enough that it happens on time. Use the manufacturers’ lists for fluids and filters; the items below are a common base for a fleet maintenance checklist.
- Engine oil and filter, with a sample for oil analysis if you run a program
- Chassis lube at every grease point, including fifth wheel and slack adjusters
- Brake adjustment check and lining or pad thickness
- Tire pressure, tread depth and wheel nut indicators
- Lights, wipers, horn and mirrors
- Fluid levels: coolant, power steering, washer and DEF
- Air system: leaks, dryer purge and tank drains
- Belts and hoses for cracks and leaks
What a B service adds
Run the full A list as part of every B. The added items take more time, so book each B for a day the truck can stay in the shop.
- Fuel filters and the fuel water separator
- Air filter restriction reading, replacing the element as the gauge or manual requires
- Coolant test for freeze point and additive level
- Battery and charging system test
- Steering and suspension: tie rod ends, kingpins, U-bolts, springs and bushings
- Driveline: U-joints, carrier bearing and slip yoke
- Exhaust aftertreatment checks the engine maker specifies, including the DPF and DEF systems
C service and the annual DOT inspection
49 CFR 396.17 bars a carrier from operating a commercial motor vehicle unless each component listed in Appendix A to Part 396 has passed an inspection within the preceding 12 months, with documentation of it on the vehicle. In a tractor and semitrailer combination, each unit needs its own inspection. The carrier can do the inspection itself or have a qualified garage, leasing company or similar business do it as its agent.
Scheduling the C service in the same visit saves pulling the truck twice. Typical C items include differential and transmission fluid changes at the manufacturers’ intervals, a coolant service when it is due, valve adjustment if the engine maker calls for one, and a full brake inspection with the wheels off. Keep the annual inspection report, because the sticker on the truck only proves an inspection happened.
Records your truck maintenance program must keep
49 CFR 396.3 requires every motor carrier to systematically inspect, repair and maintain the vehicles it controls. For each vehicle it controls for 30 consecutive days, the carrier keeps an identification of the vehicle, a means to show the nature and due date of the inspection and maintenance work, and a record of inspections, repairs and maintenance with their date and nature. Those records stay where the vehicle is housed or maintained for 1 year, and for 6 months after the vehicle leaves the carrier’s control.
The "means to indicate the nature and due date" is your PM schedule. A schedule in someone’s head or on a wall chart that gets erased does not meet it well. Electronic records are allowed under 49 CFR 390.32 if you can retain them and reproduce them accurately when asked.
Running a truck PM schedule in FleetZap
In FleetZap you set up A, B and C as separate preventive schedules on the same trucks, each by miles, engine hours or calendar, and each with its own procedure attached as a checklist. When a truck crosses an interval, FleetZap opens the work order with that checklist on it, and upcoming PM is projected from actual usage. Odometer and engine hours come from technicians in the office or the field app, or from connected telematics such as Geotab, Samsara, Motive, Azuga, Verizon Connect, Webfleet, GPS Insight, Teletrac Navman, Zonar or Linxup.
Drivers can run a daily check from the truck’s QR label on their phone, with no account needed. A failed item opens a repair work order linked back to the check and alerts the office. Every job records parts, labor, meter reading and problem codes against the truck, so its full history, cost per mile and downtime are on one page when you need them for an audit or a resale.
Key takeaways
- When you set A, B and C intervals, start from the shortest interval any component manual gives for your duty class and build the levels as multiples of it.
- Compare each truck's engine hours with its miles once a quarter; a truck that logs many hours for few miles is idling, and its oil and filter services belong on an hour trigger as well.
- Book the C service into the same shop visit as the annual 396.17 inspection to pull the truck once.
- Keep the full annual inspection report in the truck's file; an auditor can ask for it, and the decal alone doesn't show what was checked.
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Frequently asked questions
What is a truck PM service?
A truck PM service is scheduled preventive maintenance done at a set interval of miles, engine hours or time, before something breaks. Most fleets use levels called A, B and C, from a short lube, oil and inspection service to a full service that often includes the annual DOT inspection. The contents and intervals come from the manufacturers’ manuals and your duty cycle.
How often should diesel trucks get maintenance?
Follow the engine and chassis makers’ manuals, which set oil, filter and fluid intervals by miles, hours or months for each duty class. Drivers inspect every working day, the A service usually lines up with the oil drain interval, and each commercial vehicle needs an annual inspection under 49 CFR 396.17. Manuals often list shorter intervals for severe or idle-heavy duty.
What should a fleet maintenance checklist for trucks include?
A truck checklist should cover brakes and brake adjustment, tires and wheels, steering and suspension, lights and reflectors, the air system, fluid levels, belts and hoses, coupling devices and emergency equipment. Add engine oil and filters, chassis lube and aftertreatment checks at the A, B and C levels. Use the parts and accessories listed in 49 CFR 396.11 as the daily minimum.
What is the difference between A, B and C service on a truck?
An A service is the shortest, usually oil, filter, lube and a safety inspection. A B service adds fuel and air filters, coolant and battery tests and a closer look at steering, suspension and driveline. A C service is the most complete, often with drivetrain fluid changes and the annual DOT inspection. Each level includes everything in the levels below it.
How long do I need to keep truck maintenance records?
Under 49 CFR 396.3, motor carriers keep inspection, repair and maintenance records for each vehicle where it is housed or maintained for 1 year, and for 6 months after the vehicle leaves their control. Driver vehicle inspection reports and repair certifications are kept for three months under 49 CFR 396.11. Electronic records are allowed if they can be reproduced accurately.