What should you check before buying a used 6.7 Power Stroke?

Look for maintenance records first. Oil changes and fuel-filter service matter a lot on a 6.7 Power Stroke. Missing fuel-system history is a reason to slow down. Check cold starts, idle quality, coolant level, oil leaks, exhaust or emissions warnings, turbo behavior, transmission shifts, and any sign of fuel contamination. Ask whether the high-pressure fuel system has ever been repaired. CP4 failure can be expensive, so fuel quality and records matter. Inspect the rest of the truck too. Front-end wear, brakes, tires, rust, hitch setup, bed wear, idle hours, and towing history tell you how the truck lived. Be careful with heavy tuning, deleted emissions parts, vague repair stories, or sellers who cannot explain warning lights. A stock or well-documented truck is usually the safer buy.