A lot of new attention has been focused on Ford’s 6.7-liter Power Stroke diesel engine with the announcement of the new High Output version. The 6.7-liter has weathered over a decade in three generations of Super Duty Ford trucks. It has been a dependable, workhorse of a powerhouse that was engineered and produced exclusively by Ford. Now, with the 2023 6.7 HO cranking out 1,200 lb-ft of torque, buyers want to know how good, or bad, Ford’s six-seven has been.

Nothing is perfect, and there are issues that have cropped up over the diesel’s long lifespan. Some affect only certain generations, while others plague all of the six-seven generations. We’ll look at the major problems that crop up in forums and treatises. 

What are the three generations of the 6.7 Power Stroke engine?

The three generations of the six-seven are 2011 to 2014, 2015 to 2019, and 2020 to 2023 Super Duty F-Series trucks. According to our pal KJ at MotorTrend, the first generation is the one that generally has the most issues. But some of those problems have carried through to all years of the Powerstroke. 

The known problems with the first-generation diesel resulted in a revised 2015 second-gen. Torque and horsepower were increased, but reliability issues were also addressed. The same can be said for the current generation of 6.7 liters. Following are the most common problems that beset the six-seven.

Turbocharger Problems

The first-gen 6.7 used a rather unique design for its turbocharger. It was actually more like a compound turbo system with two of them in tandem. Once exhaust gasses are passed through the first turbo, the compressed exhaust goes through two smaller units to further increase its compression. 

So there is much more air volume running through the turbo. Early versions used ceramic bearings for the wheels, which failed often. Steel bearings soon replaced them with much better results. Aftermarket upgrade kits are a smart purchase to get more longevity out of this more complicated turbo setup. 

6.7 Exhaust sensor failures

There are four exhaust sensors. Unfortunately, when a sensor fails it puts the truck into limp mode. The code that is flashed will identify which of the four has failed, making diagnosis easy. And replacing them is a fairly simple process.

Turbo coolant leaks

Some posters have described coolant that puddles on top of the engine. This is caused by a leaking turbo coolant line fitting. Unfortunately, accessing it requires the removal of the upper intake manifold. But replacing the fitting and coolant line most often fixes the leak.

6.7 EGR system clogs

Though fairly robust, the main problem with the EGR system is clogging. Soot gets packed into them which will trigger a code. Though fairly easy to replace, you may need to explore the system for other less common issues. Or, you can just replace the cooler and hope the system functions like normal. 

Glow plug failure

This was a recurring problem with the first-year 6.7-liter. When the glow plugs fail, they can break apart causing catastrophic engine damage. Your best bet is to determine if the glow plugs have been updated, or replace them if you’re not sure. Replacement glow plugs run between $30 and $60 each.

Fuel pump/fuel system problems

The 6.7 Power Stroke fuel system will normally not give the owner problems. That is unless the injection pump fails. If this happens, debris will run through the entire fuel system, meaning not only the injection pump but the injectors and pressure regulators must all be replaced. Also, the entire system will first need to be cleaned up. 

One tip is to regularly replace the filters to avoid particles impacting the fuel pump. Using a better diesel blend is also recommended, rather than that old cheap stuff.