A thorough pre-trip inspection is not just a box to check — it is your first line of defense against roadside violations, breakdowns, and accidents. Under 49 CFR 396.13, drivers are required to complete a vehicle inspection report before operating a commercial motor vehicle. Failing to conduct one can result in an out-of-service order, a violation on your CSA record, and liability exposure if something goes wrong on the road.
This checklist walks through every step of a proper pre-trip inspection, from the exterior walk-around to the air brake test and trailer check.
Legal Requirements
Federal regulation 49 CFR 396.13 requires drivers to review the last driver vehicle inspection report (DVIR) before departing and confirm that any reported defects have been repaired or certified as not needing repair. Drivers must also prepare their own DVIR at the end of each trip (or day) under 49 CFR 396.11, documenting the condition of specific vehicle components.
During a DOT roadside inspection, inspectors will check whether the driver completed a pre-trip. A missing or incomplete DVIR is a common violation that goes straight to your Unsafe Driving or Vehicle Maintenance BASIC score.
Exterior Walk-Around Inspection
Start your inspection by walking around the entire vehicle. Move systematically — most experienced drivers go left-to-right, front-to-rear, then around the passenger side.
Front of Vehicle
- Headlights and turn signals — check all lamps are present, operational, and not cracked
- Bumper and front frame — look for damage, bending, or loose components
- Windshield — check for cracks, chips, or damage that impairs visibility
- Wiper blades — confirm they are intact and not deteriorated
- License plate — present and legible
Driver Side
- Mirror — properly adjusted, no cracks, mounting bracket secure
- Door and window — opens and latches properly, glass intact
- Fuel tank — cap is secure, no leaks, fuel level adequate for the trip
- Tires — check tread depth (minimum 4/32" for steer tires, 2/32" for drive tires under federal rules), look for cuts, bulges, uneven wear, and proper inflation
- Wheels and lug nuts — no missing, cracked, or loose lug nuts; no cracks in rims
- Mudflap — present and not dragging
Rear of Vehicle
- Tail lights, brake lights, turn signals — all functional
- Reflective tape and reflectors — intact and visible
- License plate light — operational
- Rear bumper or ICC bar — securely attached, not bent
Passenger Side
- Mirror the same checks as the driver side: mirror, door, tires, wheels, fuel tank (if applicable), and mudflap.
Under-Hood Checks
With the engine off:
- Engine oil level — check dipstick, top up if needed
- Coolant level — check overflow reservoir; never open the radiator cap on a hot engine
- Power steering fluid — verify level is within acceptable range
- Belts and hoses — look for cracks, fraying, glazing, or loose connections
- Air compressor — check for leaks, ensure belts are intact
- Wiring — no exposed wires, loose connections, or worn insulation
- Leaks — check for oil, coolant, or fluid pooling under the engine compartment
In-Cab Checks
Start the engine and work through the cab systematically:
- Seat belt — functional, no fraying, retracts properly
- Horn — operational
- Windshield wipers and washers — both working, fluid reservoir filled
- Heater and defroster — functional (critical in cold weather)
- All mirrors — properly adjusted for visibility
- Dashboard gauges — oil pressure, water temperature, voltage, air pressure all reading within normal ranges
- Warning lights — ABS light should illuminate during startup and then turn off
- Emergency equipment — fire extinguisher (charged, accessible), reflective triangles, spare fuses
- Steering wheel — check for excessive free play (no more than 10 degrees on a power steering system)
- Clutch and brake pedals — proper free travel and response
Air Brake System Check
The air brake check is one of the most critical parts of the pre-trip. DOT inspectors test air brakes frequently during roadside inspections, and failures here often result in out-of-service orders.
Build-Up Rate
- With the engine running, pump the brakes to reduce air pressure to about 50 psi
- The compressor should build air pressure from 85 to 100 psi within 45 seconds (single vehicle) or 3 minutes (combination)
Air Leakdown Test
- Build air pressure to governor cut-out (typically 120-145 psi)
- Turn off the engine
- With brakes released, monitor the gauges for 1 minute — loss should not exceed 2 psi for a single vehicle or 3 psi for a combination
- Apply the brakes fully and hold for 1 minute — loss should not exceed 3 psi for a single vehicle or 4 psi for a combination
Low Air Warning
- With the key on and engine off, pump the brake pedal to reduce air pressure
- The low air warning buzzer or light must activate before air pressure drops below 60 psi
Spring Brake Test
- Continue pumping until air pressure drops to approximately 20-45 psi
- The spring brakes (parking brakes) should apply automatically
- Verify the vehicle cannot be moved with spring brakes applied
Trailer Inspection
If pulling a trailer, inspect it before coupling and again after:
Before Coupling
- Landing gear — fully raised and crank handle secured
- Kingpin — not bent, cracked, or excessively worn
- Apron and upper plate — no cracks or damage
After Coupling
- Fifth wheel — locked around the kingpin, release handle in the locked position, no gap between the apron and the fifth wheel plate
- Tug test — gently pull forward to confirm the coupling is secure
- Air and electrical lines — connected, no leaks, no chafing or damage
- Trailer brakes — apply and release trailer brakes to verify they function independently
- Tires — same checks as the tractor (tread depth, inflation, condition)
- Doors — latched, sealed, and secure
- Load securement — if applicable, verify cargo is properly secured and within weight limits
Documenting Defects on the DVIR
When you find a defect during your pre-trip inspection, document it on the DVIR immediately. Under 49 CFR 396.11, the report must include:
- Vehicle identification (unit number or plate)
- Date of inspection
- Each defect or deficiency found
- Driver's signature
- If no defects are found, indicate that the vehicle is satisfactory
If the previous driver's DVIR listed defects, verify that repairs were completed and signed off by a qualified mechanic before driving.
Common Violations That Cause Out-of-Service Orders
Based on CVSA roadside inspection data, these are the vehicle-related issues most likely to put you out of service:
- Brake adjustment — brakes out of adjustment beyond allowable limits
- Brake components — cracked drums, worn linings, air leaks in brake chambers
- Tires — tread below minimum depth, exposed cord, flat tires
- Lighting — inoperative required lamps (headlights, tail lights, turn signals)
- Coupling devices — fifth wheel not locked, missing safety devices
- Cargo securement — inadequate tie-downs, shifting loads
A disciplined pre-trip inspection catches every one of these issues before you leave the yard.
Key Takeaways
Pre-trip inspections protect your CDL, your CSA scores, and your safety. Build a consistent routine so that every check becomes second nature. Document everything on the DVIR — it takes five minutes and saves you from hours of delay at a roadside inspection.
Use a fleet compliance system to digitize DVIRs, track defect resolution, and keep inspection records organized for audits. The best carriers treat pre-trip inspections as non-negotiable, and their safety records prove it.