What to Do When Your Truck Breaks Down on the Highway

A breakdown on the highway is every trucker's nightmare — but how you handle the first 15 minutes can be the difference between a minor delay and a major incident. Here's the complete playbook.

Step 1: Safety First — Get Off the Road

The moment you sense something wrong — unusual noise, loss of power, warning lights — your first priority is getting the truck safely off the road. Do not stop in a travel lane.

• Activate your 4-way hazard lights immediately
• Steer toward the right shoulder or emergency lane
• If possible, exit at the next off-ramp — even a broken truck can often roll to an exit
• Aim for well-lit, visible areas — avoid curves or hills where you can't be seen
• If you can reach a truck stop, do it — you'll have more resources there

Step 2: Secure the Scene

Once stopped, make yourself visible to oncoming traffic:

• Keep hazard lights on
• Place reflective triangles: one 10 feet behind the truck, one 100 feet back, one 200 feet back
• If it's dark, use flares in addition to triangles
• Stay inside the cab or behind a guardrail — never stand between your truck and traffic
• Put on your safety vest if you have one

FMCSA regulations require you to place warning devices within 10 minutes of stopping on a highway. This is both a legal requirement and a life-saving measure.

Step 3: Assess and Document

Before making any calls, do a quick assessment:

• What warning lights are on?
• What did you hear/feel before stopping?
• Is there smoke, steam, or fluid under the truck?
• What is your exact location (mile marker, cross street, GPS coordinates)?
• What is the condition of your load?

Take photos of the truck, any visible damage or fluid leaks, and your location. This documentation helps mechanics diagnose remotely and protects you for insurance purposes.

Step 4: Make the Right Calls in the Right Order

Call 1: Your Motor Carrier or Dispatcher

If you're a company driver, call your dispatcher first. They may have a preferred breakdown service, insurance requirements for repair authorization, or a dedicated breakdown line. Do not authorize major repairs without their approval — it may affect your reimbursement.

Call 2: Roadside Assistance or Breakdown Service

If you're an owner-operator, call your roadside assistance provider:

• OOIDA (Owner-Operator Independent Drivers Association) offers roadside plans
• Many fleet fuel cards include breakdown assistance (Comdata, EFS, TCS)
• Some truck stops have posted numbers for local mobile mechanics

Call 3: A Local Diesel Mechanic

Use Diesel Mechanic Finder to locate the nearest mobile mechanic or 24/7 shop. Filter by your current state and look for mobile repair options if you can't get the truck to a shop.

Step 5: Diagnose Over the Phone

A good diesel mechanic can often make a preliminary diagnosis based on your description of the problem. Be ready to tell them:

• Engine make and model (e.g., Cummins ISX15, Detroit DD13)
• Truck year, make, model
• Fault codes (if you have a code reader) or warning lights on dash
• What the truck did before it stopped
• Whether it will still start and run
• Approximate mileage on the truck
• Recent maintenance performed

Step 6: Know When to Tow vs. Repair Roadside

Some problems can be fixed roadside. Others require a shop.

Typically repairable roadside:

• Air line breaks or fittings
• Minor electrical issues (bad sensor, loose connection)
• DPF forced regen
• Tire blowouts
• DEF system issues (if the truck isn't in full derate)
• Belts and hoses (if the mechanic carries parts)

Requires a shop:

• Engine internal failure (bearings, pistons, valves)
• Turbocharger replacement
• Transmission overhaul
• Major fuel system work
• Anything requiring a lift or press

Step 7: Protect Your Load

While waiting for help, think about your cargo:

• Is it temperature-sensitive? Alert the shipper or receiver immediately
• Is it hazmat? You may have additional notification requirements
• Is the trailer secure? Check that landing gear is down if decoupled
• Document the trailer condition for insurance purposes

Step 8: Keep Records for Later

Every breakdown is a learning opportunity and a financial event. Keep:

• Repair invoices (for tax deductions and warranty tracking)
• Photos of the breakdown and any damage
• Contact information for the shop that helped you
• Time and mileage of the breakdown

Emergency Breakdown Checklist

• ✅ Hazard lights on
• ✅ Safely off the road
• ✅ Warning triangles placed
• ✅ Dispatcher/carrier notified
• ✅ Location documented
• ✅ Photos taken
• ✅ Mechanic called
• ✅ Cargo situation assessed

A breakdown doesn't have to derail your week. With the right preparation and the right resources, most drivers are back on the road within hours.