5 Common Reasons People Fail BIT Inspections (And How to Avoid Them)

If you operate commercial vehicles in California, you know that BIT inspections (Basic Inspection of Terminals) are mandatory every 90 days. These inspections ensure that trucks, trailers, and commercial fleets meet safety regulations, preventing accidents and keeping roads safe.

However, many businesses fail their BIT inspections due to avoidable issues, leading to costly downtime, fines, and compliance headaches. In this guide, we’ll break down the five most common reasons fleets fail BIT inspections—and, more importantly, how to pass with flying colors.

1. Faulty Brakes and Air Systems

One of the biggest reasons trucks fail a BIT inspection is brake system violations. Since air brakes are critical for stopping power, inspectors focus on:

Common Brake Issues That Lead to Failure:

• Worn-out or cracked brake linings
• Air leaks in the brake system
• Slack adjusters out of spec (over 2 inches of travel)
• Low air pressure build-up rates
• Malfunctioning brake chambers

How to Avoid a Brake System Violation:
✔ Perform daily brake checks before hitting the road.
✔ Listen for hissing sounds that indicate air leaks.
✔ Check slack adjuster travel and keep it within the correct range.
✔ Have a technician inspect brake pads and replace them before they wear out.

Pro Tip: If your truck loses air pressure too quickly, you likely have a leak in the system—and that’s an automatic failure!

2. Worn or Underinflated Tires

Another major reason fleets fail BIT inspections is bad tires. California DOT inspectors check for:

Common Tire Violations:

• Tread depth below 4/32” on steer tires (2/32” on drive tires)
• Uneven wear patterns (indicating alignment or suspension issues)
• Overinflated or underinflated tires
• Sidewall cracks, bulges, or dry rot

How to Keep Your Tires BIT-Ready:
✔ Check tire pressure weekly with a calibrated gauge.
✔ Rotate and align tires to prevent uneven wear.
✔ Inspect sidewalls and tread depth regularly.
✔ Replace tires before they reach the legal limit.

Pro Tip: Running tires below the recommended PSI can lead to blowouts, increased fuel costs, and automatic inspection failure.

3. Bad Lighting & Electrical Issues

A simple burned-out light can fail your BIT inspection. Since visibility is crucial for safety, inspectors focus on:

Common Lighting & Electrical Failures:

• Burned-out headlights, brake lights, or turn signals
• Damaged wiring or exposed electrical connections
• Corroded or loose battery terminals
• Malfunctioning ABS warning lights

How to Avoid Electrical Violations:
✔ Do a pre-trip light check before every shift.
✔ Clean battery terminals to prevent corrosion.
✔ Inspect wiring for frays, breaks, or loose connections.
✔ Keep extra fuses and bulbs in your truck.

Pro Tip: LED upgrades are brighter and last longer, reducing the chance of a burned-out bulb costing you a passing grade!

4. Leaking Fluids & Engine Issues

BIT inspectors hate leaks—whether it’s oil, coolant, transmission fluid, or fuel. Even a small drip can lead to a failed inspection.

Fluids That Can Cause a BIT Failure:

• Oil leaks (common around gaskets and seals)
• Coolant leaks (often from hoses or the radiator)
• Fuel leaks (a serious fire hazard)
• Power steering and brake fluid leaks

How to Prevent Fluid Leaks:
✔ Inspect the engine bay and undercarriage weekly for drips.
✔ Tighten loose hoses, clamps, and fittings.
✔ Replace worn gaskets before they fail.
✔ Use leak detection dye for hard-to-find leaks.

Pro Tip: A minor leak today could become a major breakdown tomorrow—don’t ignore small fluid drips!

5. Loose, Broken, or Missing Suspension Components

The suspension system plays a critical role in ride quality and load stability, so DOT inspectors check for any signs of damage.

Suspension Red Flags That Cause BIT Failures:

• Cracked or broken leaf springs
• Loose U-bolts or suspension bolts
• Worn-out shock absorbers (causing excess bouncing)
• Air suspension leaks (bags should maintain pressure)

How to Keep Your Suspension in Compliance:
✔ Check leaf springs for cracks or shifting.
✔ Inspect shock absorbers for leaks or weak damping.
✔ Ensure air suspension bags hold pressure without leaking.
✔ Tighten all suspension bolts to manufacturer specs.

Pro Tip: A sagging or leaning truck is a dead giveaway that your suspension needs repairs before an inspection!

How to Prepare for a BIT Inspection

To ensure you pass every BIT inspection, follow these best practices:

Perform Pre-Trip Inspections:

• Walk around your truck and check for leaks, tire issues, and bad lights.
• Test brakes, suspension, and air systems.

Keep Up with Preventive Maintenance:

• Change fluids regularly and inspect belts & hoses.
• Replace worn-out brake pads, seals, and tires before they fail.

Maintain Accurate Records:

• Keep a log of all repairs and inspections.
• Have your BIT records organized and accessible.

Work with a Professional Repair Service:

• A trusted mobile maintenance team can catch issues early and prevent failures.
• Schedule regular DOT-level inspections to stay compliant.

Final Thoughts

BIT inspections aren’t optional—they're mandatory every 90 days, and failure can lead to fines, downtime, and even a revoked operating permit. By addressing brake issues, tire wear, fluid leaks, electrical failures, and suspension problems, you can keep your fleet compliant and on the road.

For BIT inspection prep and mobile maintenance services in Brea, CA, trust A Plus Mobile Maintenance! Our team will inspect, repair, and ensure your trucks pass BIT inspections hassle-free.