Just saw a huge difference in my truck's fuel mileage after cleaning the EGR cooler

My 2015 Duramax was only getting about 13.5 mpg on the highway for the last six months. I finally pulled the EGR cooler last weekend and it was almost completely clogged with soot. After a good overnight soak in cleaner and a pressure wash, I put it back together. Just did a 200-mile run and the trip computer showed 16.8 mpg. I knew a dirty EGR system hurt performance, but I didn't think the hit to fuel economy would be that big. Has anyone else seen this much of a jump just from cleaning one component?

3 comments

3 Comments

hugos461mo ago

Remember my neighbor's old Ram 3500. He was complaining about terrible mileage for months, then his kid cleaned the EGR valve and cooler. Said it was like a whole different truck after that, mileage shot right up.

evahenderson1mo ago

My brother-in-law's 2012 Powerstroke had the same issue last fall. His mechanic said a clogged EGR cooler can drop mileage by 2-3 mpg because the engine has to work so much harder to push exhaust gases through. Your numbers line up with what he saw after his cleaning.

susan_adams1mo ago

Oh man, that tracks. My buddy's old Duramax was getting awful mileage, and his shop found the EGR cooler totally packed with gunk. He got a bunch of his mpg back after they cleaned it out.