Derate Update 2027

[Timd32]

So I read an RV article maybe that went over the DEF Derate BS, and I'll super summarize the worse case proposed for 2027 will be derated to 50MPH at the 60HR mark.

It did say it is also proposed that the MFG will have the option to go back and change the programming. I would hope they do.

It went over the current deal with the sensor reading error due to poor product quality stranding RVs. And it would use different set of readings.

I'm not 100% if this was all classes of Diesel trucks, but the current set up was to prevent folks from just filling the DEF tank with water say or diluted DEF of unknown quality. But what they found with this latest failure is (don't want to say zero) but was almost no DEF quality issues with the rigs stopping.

Why it takes these folks 5 more years to figure this out and just admit the current set up is beyond flawed. I know it's not easy to say you screwed up. But it's come up a time or two as a reason for some to stay away from newer rigs.

 

[Wiredawg]

I can't speak to all DEF setups, but there is an issue been going on with medium duty Super Cs Freightliner and International, there may be others. There is a coolant valve that default (unpowered) state is open. The truck computer cuts power to the valve that opens it when coolant is needed to heat the DEF tank. These valves are failing in open state and frying the electronic card in the Quality Level Sensor (QLS), reads DEF tank is empty, and begins derate process. International and Cummins have a temporary EPA approved bypass for the program, but you still have to run DEF. I simply installed a manual ball valve closed in front of the coolant valve. Easy peasy. Lots of folks have parked RVs, but it's the same on the commercial vehicles too. This is what I'm familiar with anyway.

 

[Timd32]

Found in my history.

I don't see a way to move this into the general or RV section, looks like I put it in 4th Gen, either way. It seems related to a bunch of general Diesel powered stuff.

https://www.rvtravel.com/motorhomers-alert-epa-proposes-def-derate-rules-1052b/

 

[sag2]

I can't speak to all DEF setups, but there is an issue been going on with medium duty Super Cs Freightliner and International, there may be others. There is a coolant valve that default (unpowered) state is open. The truck computer cuts power to the valve that opens it when coolant is needed to heat the DEF tank. These valves are failing in open state and frying the electronic card in the Quality Level Sensor (QLS), reads DEF tank is empty, and begins derate process. International and Cummins have a temporary EPA approved bypass for the program, but you still have to run DEF. I simply installed a manual ball valve closed in front of the coolant valve. Easy peasy. Lots of folks have parked RVs, but it's the same on the commercial vehicles too. This is what I'm familiar with anyway.

Actually the early Cab Chassis trucks had coolant heated DEF tanks. The valve would also stick open and cook the water out of the DEF making the concentration go too high and plugging everything up.