What is the real fix for my LML Duramax EGR cooler clogging every 40k miles?

[CumminsKev02]

My stock 2014 GMC 2500 (115k miles) just threw P2457 (EGR Cooler Efficiency) right after I spent hours cleaning the caked soot out of the valve for a P0401 code. Coolant temps are creeping up under load.

1. Does P2457 mean the cooler core is totally plugged, or is it leaking internally?
2. If I can't delete due to emissions, are those aftermarket stainless steel coolers worth the money?
3. If I just say screw it and delete, what's the best mild tune that won't fry my stock trans?

 

[Rusty73L_Guy]

If you live in a strict emissions state like California or New York and absolutely cannot delete, yes, aftermarket upgraded stainless steel coolers are 100% worth the money.
The factory GM cooler uses fragile, thin-walled aluminum tubes that clamp soot like a magnet and break easily. The upgraded aftermarket units use heavy-duty, radiused stainless steel helical tubes. They allow better exhaust flow, are way more resistant to clogging, and practically eliminate the risk of internal cracks that cause hydro-locking. It’s a permanent 'fix' for a stock truck, but you still need to drive it hard on the highway occasionally to burn off the carbon.

 

[ZF6_Zach]

To answer your first question: P2457 means the cooler core is physically blocked with carbon, not leaking yet. The ECM triggers this code because the temperature sensors before and after the cooler show that the exhaust gases aren't dropping to the target temperature.

The fact that your coolant temps are creeping up under load confirms it—the exhaust gases are either totally blocked or flowing through a tiny, restricted area, turning the cooler into a solid heat brick that is heating up your cooling jacket. If it were leaking internally, you would be blowing sweet-smelling white smoke on cold starts and your coolant reservoir would be dropping. Right now, it's just a massive brick of baked soot.