Complete Guide to DOT Vehicle Maintenance & Inspection Compliance

Vehicle maintenance isn't just about keeping your trucks running — it's a federal requirement. Under FMCSA Part 396, every motor carrier must systematically inspect, repair, and maintain all commercial motor vehicles under its control. Brake violations alone account for over 30% of all roadside out-of-service orders, making vehicle maintenance the single most impactful compliance area for your fleet.

This comprehensive guide covers every aspect of DOT vehicle maintenance compliance and links to deeper guides on specific topics.

Annual DOT Inspections (§396.17)

Every CMV — including tractors, straight trucks, and trailers — must pass an annual inspection performed by a qualified inspector. The inspection must cover all items listed in Appendix G of Part 396, including:

• Brake system (service brakes, parking brake, brake drums/rotors, hoses, tubing)
• Coupling devices (fifth wheel, pintle hook, drawbar)
• Exhaust system
• Fuel system
• Lighting devices (headlights, tail lights, turn signals, reflectors)
• Steering mechanism
• Suspension (springs, U-bolts, air bags)
• Frame and frame assemblies
• Tires (wear, inflation, condition)
• Wheels, rims, and lugs
• Windshield wipers and glazing

The inspection report must be kept on the vehicle or at the carrier's principal place of business for 14 months. A copy of the report or the inspection decal must be displayed on the vehicle.

Driver Vehicle Inspection Reports — DVIRs (§396.11-396.13)

Drivers must complete a written Driver Vehicle Inspection Report (DVIR) at the end of each day's work on every vehicle operated. The DVIR must cover:

• Service brakes and parking brake
• Steering mechanism
• Lighting devices and reflectors
• Tires, horn, windshield wipers
• Rear vision mirrors
• Coupling devices (for combination vehicles)
• Wheels and rims
• Emergency equipment (fire extinguisher, triangles)

If a defect is reported, the carrier must repair it before dispatching the vehicle, and a signed certification of repair must be on the DVIR. Carriers must retain DVIRs for 3 months.

Related: DVIR Best Practices: How to Never Fail a Roadside Inspection

Preventive Maintenance Programs (§396.3)

Every motor carrier must have a systematic inspection, repair, and maintenance program for each vehicle under its control. The program must include:

• Regular inspection intervals based on mileage or time
• A written maintenance schedule for each vehicle
• Documentation of all inspections and repairs performed
• Procedures for reporting and correcting defects

There's no FMCSA-mandated PM interval — carriers set their own based on vehicle type, age, and operating conditions. Common intervals are every 15,000-25,000 miles or every 90 days.

Related: How to Build a DOT-Compliant Preventive Maintenance Program

Maintenance Records (§396.3)

For every vehicle, you must maintain records showing:

• Identifying information (make, model, year, VIN, license plate)
• A schedule of inspections to be performed
• A record of all inspections, repairs, and maintenance performed
• Date, mileage, and nature of each repair

Records must be retained for 1 year while the vehicle is active, plus 6 months after the vehicle is disposed of.

Roadside Inspections

FMCSA and state DOT officers conduct roadside inspections at weigh stations and checkpoints. There are six levels:

• Level I — Full inspection (driver + vehicle)
• Level II — Walk-around driver/vehicle inspection
• Level III — Driver-only inspection (credentials, logs)
• Level IV — Special inspections (one-time examination)
• Level V — Vehicle-only inspection (without driver present)
• Level VI — Enhanced inspection for radioactive shipments

Top Vehicle Out-of-Service Violations

• Brake adjustment — Brakes out of adjustment beyond allowed limits
• Brake hoses/tubing — Chafed, crimped, or leaking brake lines
• Tire condition — Flat, audibly leaking, or below minimum tread depth
• Lighting — Inoperable required lamps or missing reflectors
• Cargo securement — Improperly secured loads