White Smoke or Hazing Exhaust on LB7 Duramax

Texas Diesel Company has the factory GM computer in-house! This allows us to quickly and effectively diagnose your vehicle saving you both time and money. We are also able to provide in-house programming of all components & modules installed in your vehicle, no different than the Chevrolet/GMC dealership would. If you’re another local shop interested in having us re-program a module for you, please call (903) 292-0400

Glow plug feedback circuit. This code will set any time there is an issue with a glow plug on your Duramax LB7. The ECM reads feedback voltage from the injector circuit. If you have 5.00-6.00V on your scan tool under glow plug feedback its unlikely that you have any bad glow plugs. If it reads 2.00-3.00v its likely you have 1 bad glow plug. 1.00-2.00V = 2 bad. .80 -1.70 V = 3 bad & less than 1.3V its likely you have 4 or more bad glow plugs. The best way we have found to test glow plugs is by removing them and then bench testing them. You can do this by connecting the ground from a battery pack to the body of the glow plug (usually where it screws into the head), then take the positive lead and touch it to the end of the injector that connects to the glow plug wiring harness. If the glow plug starts to smoke or turn red/orange rather quickly, then the glow plug is good. Make sure to wear eye protection while doing this and refrain from touching the glow plug as it will be very hot!