Truck DOT Inspection Checklist: Pass the First Time

Updated August 2026 · By Power Diesel

Every commercial vehicle needs an annual (periodic) DOT inspection, and a failed one means downtime and a re-check. The good news: most failures come from a short list of things you can check - or have checked - beforehand.

Here's a practical walk-through of what gets looked at and where trucks most often fail.

What the inspection covers

The federal periodic inspection looks at the safety-critical systems of the truck and trailer. In plain terms, that's brakes, tires and wheels, steering and suspension, lights and electrical, the frame and coupling, and the exhaust and fuel systems. An inspector is asking one question: is this vehicle safe to be on the road with a load?

Where trucks most often fail

• Brakes: out-of-adjustment slack adjusters, air leaks, worn linings, bad chambers. This is the #1 category.
• Tires: low tread, flat spots, exposed cord, mismatched duals, under-inflation.
• Lights: a single burned-out marker, brake or turn light fails you - and it's the easiest thing to miss.
• Steering & suspension: loose components, cracked springs, worn bushings.
• Leaks: air, oil, coolant or fuel leaks.
• Frame & coupling: cracks, a loose fifth wheel, worn parts.

Your pre-inspection checklist

• Walk every light - markers, brakes, turns, tags - and replace any that are out.
• Check tire tread and pressure on every position, including inner duals.
• Listen and feel for air leaks; make sure the truck builds and holds air.
• Look under for oil, coolant, fuel and air leaks.
• Check the fifth wheel and coupling for play and damage.
• Look at the exhaust for leaks and secure hangers.

If you find a defect

Small defects - a light, an air leak, a slack adjuster - are usually quick, cheap fixes if you catch them before the inspection. Fixing them ahead of time is far cheaper than failing, getting a re-check, and losing a day. And because we're a full mobile shop, when we inspect we can usually repair those defects right there so you leave with a passing inspection.

Frequently Asked Questions