The 7.3L Powerstroke (built by International / Navistar T444E) is widely considered the most reliable diesel Ford ever sold. Pre-emissions, simple HEUI injection, and a bottom end that routinely sees 400,000-500,000 miles. The few weak points are easy and cheap to fix.
Properly maintained 7.3L trucks regularly cross 400,000-500,000 miles. No DPF, no DEF, no EGR. Simple electronics. If you find a clean one, buy it.
The #1 stranding failure on the 7.3L. The CPS fails without warning - truck dies, no restart. $35 part. Carry a spare in the glovebox.
Get a free diagnosis →Hard winter starts trace to a failed glow plug relay (under hood) or individual glow plugs. Relay is $25 and 5 minutes to swap.
View P0670 Diagnosis →The harness that connects injectors under each valve cover melts and shorts. Symptoms: random misfires, multiple injector codes. $50 per harness.
Get a free diagnosis →7.3L injectors last 200,000-400,000 miles. Symptoms include hot hard starts, misfire, and white smoke. Set replacement runs $2,500-$4,000.
Get a free diagnosis →The high pressure oil pump reservoir o-rings dry out and leak. Hard hot starts result. $50 in O-rings fixes it.
Get a free diagnosis →The bellows between manifolds and turbo crack with age. Loss of boost and exhaust noise. $150 in updated pipes is the fix.
Get a free diagnosis →Run a free AI diagnosis tailored to your exact diesel. Get the most likely cause in under 30 seconds.
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Ford TSB 01-7-9 covers CPS failure on 1999-2003 trucks. TSB 03-8-9 addresses turbo up-pipe gasket leaks. The 7.3L has aged out of most warranty programs but Ford's service info is still useful. No major safety recalls remain open for these trucks. International issued multiple service letters on injector return line replacement that are worth following at high mileage.
If you see a check engine light, these codes most often relate to the issues above. Click any code for full diagnosis steps.
400,000-500,000 miles is common with basic maintenance. The bottom end is incredibly stout.
1999.5-2003 trucks have the best version (intercooled, electronic injection, mature platform). The earliest 1994.5-1997 trucks lack intercoolers.
For longevity and simplicity, yes. For power, towing, and modern features, the 6.7L wins. The 7.3L stops at 275 HP / 525 lb-ft.
Every 5,000 miles with 15W-40 conventional or 7,500 with synthetic. The 15-quart capacity handles long intervals well.
CPS (cam position sensor) failure - typically without warning. Carry a spare. Beyond that, glow plug relays, UVCH harnesses, and aging injectors.
Absolutely. Parts availability is excellent through aftermarket and salvage. Many fleets still run them.