2012 Denali 2500HD 6.6L Duramax Fuel Filter Replacement/Tips

Image found on google

This will help go over how to remove and replace a fuel filter on a 2012 GMC Denali 2500HD 6.6L Duramax, or equivalent. This motor has been used by General Motors for many years, and will be found in many Chevy and GMC trucks. Including the Sierra, Silverado, Express, and Savana, as well as various commercial applications.

Images found on Google

The Fuel filter will be located on the passenger side of the engine.


  • 1. Remove the passenger inner fender well. This you will need to remove several body clips and Phillips head screws along the fender.
  • 2. Disconnect the water in fuel sensor connection. It is the wire coming from the bottom of the fuel filter.
  • 3. Drain fuel filter. To avoid spilling diesel while removing the filter, you will be able to attach a hose to the port located on bottom of fuel filter. Direct the hose to a fuel suitable container, then turn the valve where the hose is connected 3 or 4 turns. Until you see fuel/water flowing. Then tighten once flow has stopped.
  • 4. Remove fuel filter. Turning the fuel filter counterclockwise and down will remove the filter assembly, be careful not to catch the wires from the fuel/water sensor on anything while removing. Then carefully guide filter out of wheel well.
  • 5. Remove the fuel/water sensor. This sensor should not be to tight but age can make them stick. You will want to brace the filter on removal but should be careful not to damage filter. They do sell a special wrench that will fit over the sensor perfectly, but if you are careful not to round the threads a standard wrench works the same. 1 5/8 seemed to fit the best on this one.


IMPORTANT: There will be O-rings. One located at the top sealing the filter to the housing. And another smaller one between the fuel/water sensor and filter. The new filter should always come with new ones, make sure to pay attention to proper fitment and pre-lube them with engine oil before installation!

  • 6. Install fuel/water sensor in new filter assembly
  • 7. Pre-fill filter assembly with diesel fuel (to avoid loosing prime)
  • 8.Install new fuel filter to vehicle.
  • 9. Plug in fuel/water sensor wiring connector
  • 10. Prime system. Located the hand primer pump located on top of the fuel filter and housing assembly. You will want to press this down several times until it becomes stiff and hard to press.
  • 11. Start vehicle and Inspect for leaks. You may need to repeat step 10 several times in order to achieve prime. (specially if you were unable to pre-fill the filter) Continue to prime and start until the vehicle runs. And then inspect area for any leaks.
  • 12. Assemble fender well.

Hopefully this information has helped! Thanks for reading.

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