5 Maintenance Mistakes That Get You Failed in a DOT Inspection
Truck mechanic in front of a truck
When it comes to keeping your truck road-ready, a Department of Transportation (DOT) inspection can make or break your day. Whether you’re a company driver or an owner-operator, failing one of these inspections can mean more than just a citation. We’re talking about out-of-service orders, fines, and missed deliveries. But the frustrating part? Most violations stem from small, preventable maintenance issues.
In this article, we’ll break down the five most common maintenance mistakes that lead to DOT inspection failures — and how to avoid them.
Neglecting Brake System Maintenance
Brakes consistently top the list of violations during roadside inspections. According to the Commercial Vehicle Safety Alliance (CVSA), more than 25% of out-of-service violations in 2023 were brake-related.
Read more about brake system maintenance here
Common issues:
Worn-out brake pads
Brake out of adjustment
Leaking air lines
Missing brake components
How to prevent it: Regular brake inspections, especially for air brakes, are essential. Look for signs of uneven wear, air leaks, or poor stopping power. Schedule professional inspections at intervals recommended by your vehicle manufacturer, or sooner if you're logging heavy miles.
Overlooking Tire Tread and Inflation
Tires are one of the easiest components to check—yet they still lead to thousands of inspection failures each year.
DOT regulations require:
Minimum tread depth of 4/32 inch on front tires and 2/32 inch on others
No sidewall damage, cuts, or exposed cords
Proper inflation based on load
Mistake to avoid: Assuming a tire is fine just because it’s holding air. Visually inspect and use a tread depth gauge regularly. Also, consider using TPMS systems (Tire Pressure Monitoring Systems) for better accuracy.
Learn more about details the legal tread depths, sidewall damage rules, and inflation guidelines for CMVs here
Covers inspection tips and safety reminders for commercial tires here
Ignoring Lighting and Reflector Defects
Lighting violations are some of the most cited during any level of DOT inspection.
Typical infractions include:
Non-functioning headlights, brake lights, or turn signals
Cracked or missing reflectors
Inadequate conspicuity tape on trailers
Why it matters: Even a single burned-out bulb can raise a red flag for inspectors. During your pre-trip inspection, test all exterior lights and replace faulty bulbs immediately. Consider carrying spares in your cab.
Pro tip: Check your trailer’s reflective tape too. If it’s faded or peeling, you’re not compliant.
Read about the official lighting and reflector requirements for commercial vehicles here
Skipping Fluid Leak Checks
You might think a minor oil or coolant leak isn’t a big deal, but DOT doesn’t see it that way.
Types of fluid leaks that will get flagged:
Oil (engine or transmission)
Coolant
Power steering
Fuel
What to do: Make it a habit to inspect beneath your truck after every shutdown. Puddles or wet streaks are your first warning signs. Schedule a repair the moment you notice recurring leaks.
Need help identifying specific fluid types? Check out this helpful fluid leak guide.
Failing to Keep Suspension and Steering in Shape
Suspension issues might not always show up in your gauges, but they show up fast during a DOT inspection.
Frequent problems include:
Worn bushings or shocks
Loose U-bolts
Cracked or damaged leaf springs
Steering components with excessive play
Impact on safety: Poor suspension doesn't just create a rough ride. It can cause uneven tire wear and make handling unsafe. You’ll want a trained mechanic to inspect the steering gearbox, tie rods, and shock absorbers during regular maintenance visits.
Learn more how inspectors examine suspension and steering systems during a Level 1 or 5 inspection here
Stay Ahead of DOT Inspections with Sounders Truck Repair
At Sounders Truck Repair, we help drivers and fleets stay compliant with full-service inspections, preventive maintenance, and DOT-readiness packages. Our certified techs know what inspectors look for—because we've seen it all.
Want to avoid these 5 mistakes? Book your next maintenance check with us and drive with confidence.
✅ Schedule now at Sounders Truck Repair hear