The 3.0L Duramax Diesel engine is impressive. It has gobs of low-end torque and will let you cruise down the highway without using much fuel. However, General Motors has identified an issue with the engine that may leave some owners in the cold. Thankfully, it’s an easy fix and may improve your heater performance tremendously.
This tip applies to any pickup or SUV with the 3.0L Duramax Diesel engine. That includes 2021 through 2024 models of the Chevrolet Silverado 1500, Tahoe, Suburban, GMC Sierra 1500, Yukon and Cadillac Escalade. The condition and fix are detailed in Technical Service Bulletin – PIT5734G
Poor Heater Performance – 3.0L Duramax Diesel – The Condition
According to the document published by General Motors:
Some customers may comment on poor or no heat. When comparing the heater core inlet hose temperature to the heater core outlet hose temperature, there will be a significant difference.
Only on certain pickup models: GDS2 can be used to compare the heater core inlet temperature sensor 3 to the heater core outlet temperature sensor 4, there will be a significant difference (example inlet temp 147 degs F and outlet temp 82 degs F, typically they are within 10-20 degs F).
Poor Heater Performance – 3.0L Duramax Diesel – The Fix
So, what’s the problem? Turns out it’s actually pretty simple- a kinked coolent hose that leads to or from the heater core:
This issue could be caused by either the heater core inlet or outlet hoses becoming twisted or kinked, and as a result, this may restrict the coolant flow.
The repair is to simply replace the kinked portion of the heater hose- or, if possible, unkink the hose and allow coolant to flow freely once again. If your truck or SUV is still under a factory warranty- this is something your dealer can do for you free of charge. If your vehicle is out of warranty- hopefully this article can give you a starting point to troubleshoot your issue and potentially provide a solution.
Zane Merva is the Executive Editor of GM-Trucks.com and the President of the New England Motor Press Association (NEMPA). A veteran automotive journalist with over 26 years of experience, Zane is a designated ‘Car Talk’ Expert and has been a contributor to The Boston Globe. He possesses a unique evaluative perspective, having road-tested more than 2,000 vehicles across every major manufacturer. While he is a recognized authority on General Motors truck platforms—including the Silverado, Sierra, and Colorado—his expertise is grounded in decades of deep competitive analysis that few in the industry can match. His commentary has been featured by major OEMs and media outlets, including Hyundai and PR Newswire