What Will Fail You on a DOT Inspection?

Keeping your rig DOT-compliant isn’t just about passing a check—it’s about keeping you, your cargo, and everyone else on the road safe. When the Department of Transportation (DOT) rolls up for an inspection, they’re not playing around. Even small issues can escalate into serious violations. 

But that’s not going to happen to you. Do you know why? Because you’re about to read our breakdown of the most common DOT inspection failures and what you need to keep an eye on before your next run!

Common DOT Inspection Failures

Faulty Brake Systems

If your air compressor, service chambers, slack adjusters, or brake shoes are malfunctioning or worn out, that’s a red flag. DOT inspectors often measure pushrod travel and inspect for air leaks, improper adjustments, or cracked drums. Any of these can land your rig out of service.

Worn-Out Tires

Inspectors don’t need to look long to catch a bad tire. Tire tread depth must meet minimum requirements: at least 4/32” for steer tires and 2/32” for others. They’ll also check for visible damage, sidewall bubbles, improper inflation, and mismatched sizes. 

Tires with exposed cords or bulges? Instant fail.

Defective Lighting and Reflectors

Your headlights, brake lights, turn signals, and reflectors must all work flawlessly. Lights are one of the most cited violations during DOT inspections. Missing or non-functioning lights don’t just hurt visibility—they’re a safety hazard. And yes, they’ll check your marker lights and reflective tape too.

Faulty Suspension Components

A compromised suspension can lead to unsafe handling and unpredictable braking. Inspectors look for cracked or missing leaf springs, leaking shock absorbers, or broken U-bolts. Any of these issues can cause poor weight distribution and vehicle instability, resulting in a serious violation.

Damaged or Missing Mirrors and Windshield Wipers

These may seem minor, but don’t underestimate them. Cracked or missing side mirrors and malfunctioning windshield wipers can seriously limit visibility, especially in bad weather. If inspectors see a chip or crack in your line of sight on the windshield, expect a violation.

Leaking Fluid Systems

DOT inspectors are hawk-eyed when it comes to leaks. That includes engine oil, coolant, brake fluid, and power steering fluid. Even small drips can be signs of bigger issues like worn seals, cracked housings, or loose fittings. Leaks don’t just impact performance—they’re considered hazardous.

Non-Compliant Logbooks and ELDs

Electronic Logging Devices (ELDs) are mandatory, and if you’re still trying to fudge your hours of service, you’re asking for trouble. DOT will scrutinize logbook entries, missing data, or false records. Violations in this category can sideline you and result in stiff penalties.

Failing Emergency Equipment

You need to have the basics onboard: three reflective triangles, a fully charged fire extinguisher, and extra fuses. Missing any of these will get you docked. And yes, the fire extinguisher needs to be properly mounted and within easy reach.

Compromised Frame and Body

Rust, cracks, or loose bolts on your truck’s frame and body will not go unnoticed. The DOT wants to see that your cab mounts, cross members, and frame rails are secure and free of damage. Structural issues not only compromise safety but also point to poor maintenance habits.

Non-Operational Horn or Steering Components

Steering system checks include your steering column, gearbox, and linkage. Excessive play in the wheel or worn components can be an instant fail. And don’t forget that horn—it has to work.

Broken or Missing Driver Credentials and Vehicle Documents

Inspectors will ask for your CDL, medical certificate, vehicle registration, and insurance documentation. They’ll also check for proper IFTA stickers and any required permits. Missing or expired paperwork? You won’t pass go.

Pro Tips to Avoid DOT Fails

Daily Pre-Trip Inspections: Make this a non-negotiable habit. Check tires, lights, fluids, and brakes before every haul.

Schedule Regular Maintenance: Don’t wait until something breaks. Use a maintenance log to stay ahead.

Clean and Organize Your Cab: A tidy cab helps you locate documents quickly and shows inspectors you take your job seriously.

Use Checklists: Develop a DOT inspection checklist specific to your truck. Update it with every new regulation.

Know Your CSA Score: Stay on top of your Compliance, Safety, Accountability (CSA) score to monitor your performance.

Call to Action

DOT inspections don’t have to be a gamble. By staying proactive and knowing what inspectors look for, you can keep your rig roadworthy and your record clean. When in doubt, have our expert team at Lawler DSL Repair in Fresno, CA, give your truck a once-over before you roll out!

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