6.0

fairly significant
Typical Repair Cost:
$6,000
Average Mileage:
101,000 miles
Total Complaints:
1 complaints

Most common solutions:

  1. replace transmission (1 reports)
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problem #1

Jul 262024

Sierra 2500 SLE 6.0L

  • Automatic transmission
  • 101,000 miles

6L90 Transmission on a 2015 GMC Sierra 2500HD should not be failing at 101,000 miles. Truck is in excellent shape and has been regularly serviced. P0741 code appeared without any forewarning... thereafter, shift patterns changed materially and the truck would not engage in 5th or 6th gear. Tranny fluid was pink (with gray tinge, suggesting that metal particles were in the fluid. Tranny would operate normally when cold, but after just a few miles, shift pattern would change (higher RPM to shift into any gear and no 5th or 6th gear). Manual electronic shifting would work in lower gears but still no 5th or 6th gear.

Visited multiple transmission shops and in each case, only remedy was to replace transmission. Replacement cost ~$3,000 in parts and $2,500 in labor, plus fluid, tax, etc. bringing the repair to $6,000. Replacement tranny has 3 year, 100,000 mile warranty and uses Sonnax valve body, converter other key components to mitigate the OEM torque failure.

Tranny shops say this is the number one transmission model (6L90) that they replace... it was used in GMC and Chevy trucks, Camaros, even Corvettes... why is there no class action suit against GM for this tranny?

- Gary H., Lambertville, US