What Is a BIT Inspection? California Compliance Guide for Semi-Trailers

If you operate commercial vehicles in California, staying compliant isn’t optional—it’s part of keeping your business running. One requirement that often raises questions is the BIT inspection.

For fleet owners and owner-operators, understanding what a BIT inspection involves—and how it differs from a DOT inspection—can help you avoid fines, reduce downtime, and keep your trailers road-ready. 

What Is a BIT Inspection? 

BIT inspection (Basic Inspection of Terminals) is a 90-day, California-specific safety inspection for commercia vehicles, while DOT (Department of Transportation) is a federal annual inspection. BIT, often performed by diesel technicians, covers vehicle maintenance, driver records, and terminal safety compliance every 90 days, whereas DOT inspections are annual nationwide safety checks. 

BIT is overseen by the California Highway Patrol and applies to carriers operating vehicles with a gross vehicle weight rating (GVWR) over 10,000 pounds. 

Unlike a standard roadside inspection, a BIT inspection looks beyond the vehicle itself. It evaluates: 

• Vehicle condition  
• Maintenance records  
• Driver qualifications  
• Safety practices  

This makes it a more comprehensive review of your entire operation—not just your trailer. 

How Often Are BIT Inspections Required? 

In California, carriers enrolled in the BIT program are typically required to perform inspections every 90 days. 

This regular schedule helps ensure that: 

• Trailers remain in safe operating condition  
• Maintenance issues are addressed early  
• Fleets stay compliant with state regulations  

Missing inspections or failing to maintain proper documentation can lead to penalties or increased scrutiny. 

What Does a BIT Inspection Include? 

While the scope can vary, a typical BIT inspection will review both equipment and documentation. 

Trailer and Equipment Checks 

Inspectors will look closely at key components such as: 

• Brakes and brake systems  
• Tires and wheels  
• Lights and electrical systems  
• Suspension and axles  
• Trailer structure and body components  

These are the same areas that commonly lead to violations if not properly maintained. 

Maintenance and Compliance Records 

Beyond the physical trailer, inspectors will also review: 

• Preventive maintenance schedules  
• Repair records  
• Inspection logs  
• Driver records  

This is where many operators run into issues—not because of equipment failure, but due to incomplete or inconsistent documentation. 

BIT vs DOT Inspections: What’s the Difference? 

Key Differences Between BIT and DOT Inspections 

• Frequency: BIT is required every 90 days, while DOT is required every 12 months. 
• Scope: BIT covers the terminal, maintenance, and driver records, while DOT focuses on the mechanical safety of individual vehicles. 
• Jurisdiction: BIT is a California-specific mandate, while DOT is a federal requirement. 
• Purpose: BIT evaluates a carrier’s terminal operations and maintenance protocols, while DOT ensures vehicles are roadworthy under federal guidelines 

Both are important, and failing either can result in fines or operational disruptions. 

Common Reasons Trailers Fail BIT Inspections 

From what we see in the field, most issues fall into a few categories: 

• Worn brake components  
• Underinflated or damaged tires  
• Faulty or non-functioning lights  
• Suspension wear or alignment issues  
• Missing or incomplete maintenance records  

The good news is that most of these are preventable with routine checks and timely repairs. 

Operating in California comes with stricter compliance requirements compared to many other states. For fleets running through Southern California, having a reliable partner for inspections and maintenance can make a big difference. 

At Great Western Trailer’s Fontana location, we work with fleets and owner-operators to help keep trailers aligned with both BIT and DOT requirements—so you can stay focused on the road ahead. Contact our Service Department to schedule your BIT or DOT inspections today!