Does the DOT require a PM program?

49 CFR 396.3 requires motor carriers to systematically inspect, repair and maintain their vehicles and keep records, but it does not set mileage intervals.

How often should a semi-truck get a PM?

Follow the manufacturer schedules and adjust for operating conditions and the fleet's own history. There is no single federal interval.

How long must PM records be kept?

Under 396.3(c), for 1 year where the vehicle is housed or maintained, and 6 months after the vehicle leaves the carrier's control.

How to Run a PM Program for a Fleet

What a PM program is for

Preventive maintenance is planned service done on a schedule, before something breaks. A good PM program catches worn brakes, leaking hoses, low tread and failing batteries while the truck is in for service, instead of at the roadside. It also gives the fleet the records it needs.

Federal rules require it in general terms. Under 49 CFR 396.3(a), every motor carrier must systematically inspect, repair and maintain, or cause to be systematically inspected, repaired and maintained, all motor vehicles subject to its control, and parts and accessories must be in safe and proper operating condition at all times. The regulation does not set mileage intervals. Each carrier, and the shop that serves it, designs the program.

Step 1: Build a complete unit list

Start with an accurate list of every unit in the program:

Unit number, VIN, make, model and year.
Engine and transmission models.
Current mileage or engine hours.
Body or trailer type and any special equipment, such as liftgates or refrigeration units.
Date of the last PM and the last DOT annual inspection.

This matches what 396.3(b) requires motor carriers to keep: an identification of the vehicle including company number if marked, make, serial number and year. See VIN.

Step 2: Set intervals

Intervals should come from:

Manufacturer maintenance schedules for the engine, transmission, axles and aftertreatment.
Operating conditions: severe duty, short-haul stop-and-go, idle time, dust, cold.
The fleet's own history: what fails, and how often.

Intervals can be in miles, engine hours, calendar time, or whichever comes first. Many programs use service levels, often called A, B and C, where each level adds tasks. For example, a basic level covers lubrication, fluid checks and a safety inspection, and higher levels add filter changes, fluid changes and more detailed inspections. Define what each level contains in writing. See PM service.

Step 3: Use a standard checklist

Every PM should follow the same checklist for that service level, so results are consistent no matter which technician does it. A good checklist:

Lists every item to inspect, service or measure.
Records measurements, such as tire tread depth and brake pushrod stroke, rather than just "OK."
Uses the same pass and fail standards as the DOT annual inspection where items overlap. Appendix A to Part 396 lists the minimum periodic inspection standards, such as brake adjustment and tire tread limits.
Has space for notes and photos.

See semi-truck PM service checklist.

Step 4: Combine PMs with the annual inspection

49 CFR 396.17 requires each commercial motor vehicle to be inspected at least once every 12 months. Many fleets schedule the annual inspection with a PM so the truck is out of service only once. The inspector must meet the qualifications in 49 CFR 396.19. See DOT annual inspection checklist.

Step 5: Schedule before units come due

The hardest part of a PM program is getting the truck to the technician on time. Practical steps:

Track due dates and mileage in one place, updated with current odometer readings.
Send reminders to the fleet a set time before each unit is due.
Offer appointment windows that fit the fleet's routes, such as nights or weekends at the yard.
For mobile service, group units at the same location into one visit.

Track the percentage of PMs completed on time each month. That single number shows whether the program is working.

Step 6: Handle defects found during PMs

A PM often uncovers repairs. Decide with the fleet how they are handled:

Safety-critical defects that would put the vehicle out of service are fixed before the truck goes back on the road. Under 49 CFR 396.7, a motor vehicle must not be operated in a condition likely to cause an accident or a breakdown.
Other defects are quoted and approved, or scheduled for later.
Every defect is recorded with the correction or the decision to defer it.

Step 7: Connect PMs with driver reports

Drivers see problems between services. Under 49 CFR 396.11, drivers must prepare a written report at the end of each day's work covering specified parts and accessories, and carriers must repair listed defects that would affect safe operation and certify the repair. Feed those reports into the PM program: a recurring complaint is a sign that an interval or a checklist item needs to change. See DVIR.

Step 8: Keep the records

Under 49 CFR 396.3(b), the motor carrier must keep for each vehicle:

An identification of the vehicle.
A means to indicate the nature and due date of the various inspection and maintenance operations to be performed.
A record of inspection, repairs and maintenance indicating their date and nature.

Under 396.3(c), those records must be kept where the vehicle is housed or maintained for 1 year and for 6 months after the vehicle leaves the carrier's control. A shop that runs a fleet's PM program should give the fleet records that meet these needs. See how long to keep truck maintenance records.

Step 9: Review and improve

Every quarter, review:

PMs completed on time.
Roadside breakdowns and their causes.
Defects found per PM, by system.
Cost per unit or per mile, if the fleet tracks it.

Using consistent repair codes, such as VMRS, makes these comparisons easier across units and vendors. See VMRS codes. Adjust intervals and checklists based on what the data shows.

Who owns the program

A PM program needs one named owner on each side. At the fleet, that is usually the fleet manager or maintenance coordinator, who keeps the unit list current and gets trucks to service. At the shop, it is a service writer or manager who watches due dates, books appointments and sends the records. When both owners meet briefly each month to review what is due, what slipped and what defects are waiting, the program stays on track. When no one owns it, PMs slip quietly until a breakdown exposes the gap.

Planning parts and labor

A predictable PM schedule lets the shop plan ahead. Stock the filters, fluids, belts and brake parts that the fleet's units use, matched by make and engine. Estimate labor per service level from your own completed repair orders, and use those figures to staff the days when many units are due. For mobile work, load the service truck with the parts for every unit on the day's route before leaving. Running out of a filter on site turns a planned PM into a second trip.

Communicating results to the fleet

After each PM, send the fleet a short summary: services performed, measurements taken, defects found, repairs completed, repairs recommended, and the next due date. Fleet managers can then plan deferred work, budget for it and answer questions from drivers or auditors without calling the shop.

Common mistakes

Intervals copied from another fleet with different duty.
Checklists with check marks but no measurements.
PMs that slip because no one owns the schedule.
Defects found but never repaired or deferred in writing.
Records kept only on paper in a technician's truck.

How MetaFleet helps

MetaFleet supports preventive maintenance programs with reminders, digital inspections and DVIRs built from your own PDF form, and a fleet customer portal where fleet managers can request a PM or inspection. Get a walkthrough.