Just thought I'd share a little issue I'm having with my 2017 F-450. On long, steep grades pulling at sustained higher boost I can get a check engine light to come on that kicks up a code: P026A- Charge Air Cooler Efficiency Below Threshold. Only happens under sustained high load conditions after I top the hill. Coolant in the secondary system is full and I changed out the cold air side temp sensor with no change. Suspected maybe the water/air intercooler was getting dirty inside and not cooling efficiently (old temp sensor was fairly dirty). I currently don't have the time or space to dig into it myself so took it to a well-known local tech that I trust.

He scoped the water/air cooler and it was surprisingly clean inside. The secondary water pump seems to be circulating coolant fine as the fluid temp is not rising with boost in shorter intervals (apparently if there's a circulation issue the water temp will climb quickly). So he turned attention elsewhere. Stuck the bore scope down in between the AC condenser (I think?) and the secondary radiator and said "I think I found your problem." He showed me the picture he snapped and that radiator was completely plugged full of bugs. Worse than I've personally ever seen on a vehicle. The condenser on the outside doesn't look bad through the grille, but the bugs were definitely finding their way through to that radiator. I bought the truck with 113k miles on it and the primary radiator was supposedly changed around 109K. I wish whoever did that work would have taken the time to wash out the other coolers while everything was apart.

To do it right it gets a bit labor intensive to pull all of the coolers out, steam clean them, reinstall, and refill/charge systems. To the tune of $900+ on the estimate. Another diesel mechanic friend of mine agrees with the estimate and says he has had luck with a long tube specialty water nozzle he built. Still involves taking coolers loose to get space to get the tube between them, but doesn't require breaking loose hoses on anything. So now I get to decide if I spend a day of my time trying to shortcut clean it outside when spring gets here, or spend the money to have it done.

Moral of the story I guess is don't overlook getting a screen in front of these trucks if you live in a area with bugs. I've always put a piece of metal door screen in front of my other trucks' radiators. I'll be doing the same with this one when I get this sorted.