Buying a Used Semi Truck: The Inspection Checklist

A used Class 8 truck is the biggest purchase most owner-operators ever make, and sellers know buyers fall for clean paint and chrome. This checklist goes from cheapest checks (paperwork, VIN) to most expensive (a shop inspection), so you can walk away early from bad trucks.

1. Paperwork and identity

Do this before you drive anywhere to look at the truck.

• VIN. Get the 17-character VIN and run it on SemiLife. Confirm the year, make, model and engine match the listing.
• Title. The title should be in the seller's name (or the dealer's), with no lienholder listed — or a signed lien release. Be wary of salvage, rebuilt or out-of-state titles you can't explain.
• Liens. Search UCC filings with the Secretary of State where the seller is based. A lender's lien can follow the truck.
• Title history. An NMVTIS report from an approved provider can show title brands, salvage and odometer records reported by states and insurers.
• Recalls. Check open safety recalls by VIN. Ask for proof that completed recalls were done at a dealer.
• Inspection history. SemiLife's VIN check shows roadside inspections tied to that VIN, which can reveal past defects and who ran the truck.
• Maintenance records. Oil changes, overhaul invoices, aftertreatment work, warranty claims. No records doesn't mean no truck, but it lowers the price.

2. The ECM report

The engine control module records how the truck was driven. Ask for a report pulled by a shop you choose — not a photo from the seller. Look at:

3. Engine and aftertreatment

• Cold start. Ask that the truck not be started before you arrive. Watch for hard starting, white or blue smoke, and knocking.
• Blow-by. Excess crankcase pressure from the breather tube can mean worn rings.
• Leaks. Oil, coolant, fuel. Check under the truck and around the head, turbo and oil cooler.
• Coolant. Look for oil in coolant or coolant in oil (milky dipstick). Ask about EGR cooler history.
• Turbo. Shaft play, oil in the intake, whistling.
• Oil analysis. A lab oil sample can show coolant, fuel dilution or metals that point to internal wear. Worth every penny.
• DPF, SCR, DEF system. Ask when the DPF was last cleaned or replaced. Check DEF quality and any SCR or NOx sensor codes. These parts are expensive.
• Emissions delete. Removing or defeating emissions equipment is illegal under the federal Clean Air Act. In California, most heavy trucks must also have 2010 or newer model year engines under the CARB Truck and Bus Regulation. A deleted truck can be hard to register, insure, sell or legally run.

4. Frame, suspension and driveline

• Frame rails. Look for cracks, welds, fish plates and rust, especially around crossmembers and suspension mounts. A welded frame needs an explanation.
• Alignment and tire wear. Uneven wear points to alignment, suspension or bent parts.
• Air suspension. Check bags for cracks, leveling valves, shocks and bushings.
• Driveline. U-joint play, carrier bearing, leaking hub seals, rear-end noise.
• Fifth wheel. Wear, play, lock function and mounting.
• Transmission and clutch. Automated manual (AMT) fault codes and shift quality on the test drive; for manuals, clutch engagement and grinding.

5. Brakes, tires and safety items

These are also the most common roadside inspection violations, so they cost you twice.

• Brakes. Pushrod stroke within limits, slack adjusters, drums or rotors, linings, air leaks. Build-up time and governor cut-out should be normal.
• Tires. Federal minimum tread depth is 4/32 inch on steer tires and 2/32 inch on others (49 CFR 393.75). Check age (DOT date code), cuts and mismatched tires.
• Lights and wiring. All lights, plus corrosion in harnesses and connectors.
• Glass and mirrors. Cracks in the driver's view are a violation.
• Annual inspection. Ask for the current annual inspection report required by 49 CFR 396.17.

6. Cab, sleeper and accessories

• HVAC and APU. Run the heat, A/C and APU. Repairs here are a quality-of-life and cost problem.
• Electrical. Dash lights, gauges, power windows, inverter, batteries.
• Water leaks. Stains on the headliner or sleeper floor.
• Seats, bunks, cabinets. Wear and smells tell you how the truck was lived in.

7. The test drive

Drive it loaded or with a trailer if possible, for at least 30 minutes, including highway speed and a hill.

• Smooth power, no smoke under load.
• No coolant temperature creep or overheating.
• Straight tracking with hands light on the wheel.
• Engine brake works on all settings.
• No new warning lights. Recheck codes after the drive.

8. Get an independent pre-purchase inspection

Pay a heavy-duty shop you choose — not one the seller recommends — to do a full inspection and ECM download. Ask for a written report with repair estimates. Use it to negotiate or walk away.

9. After you buy

• Register and title the truck; get your own insurance before you drive it.
• File IRS Form 2290 (heavy vehicle use tax) for trucks with a taxable gross weight of 55,000 pounds or more (IRS Form 2290).
• Set up IRP plates and IFTA if you'll run interstate under your own authority (or confirm your carrier handles them if leased on).
• Start a maintenance reserve from week one. See the real math of owning a truck.

Printable quick checklist

• VIN checked: year, make, model, engine match; recalls and inspection history reviewed
• Title in seller's name, no lien or a signed lien release; UCC search done
• Maintenance records reviewed
• ECM report pulled by my shop: hours, idle %, fuel economy, fault codes, regens
• Cold start, no excess smoke or blow-by, no leaks
• Oil sample sent to a lab
• DPF/SCR/DEF condition checked; no emissions delete
• Frame free of cracks and unexplained welds
• Suspension, driveline, fifth wheel checked
• Brakes and tires within limits; current annual inspection
• HVAC, APU, electrical, cab and sleeper checked
• 30+ minute test drive, codes rechecked after
• Independent pre-purchase inspection report in hand