Autoblog and Yahoo may earn commission from links in this article.Shuddering Eight-SpeedsGeneral Motors is still working on a fix for its eight-speed automatic transmissions, particularly the ones in the GMC Sierra and the Canyon. These two models are both equipped with the eight-speed automatic transmission, and the 2023 to 2026 model years are affected.It's been reported by owners that there is "a surge or shudder" while driving on the highway under light throttle. The thing is, GM knows that there is an issue and has sent out service bulletins, but no recall notice has been filed yet at the time of writing.GMCService Bulletin #1GM Authority got the specifics on the bulletins that GM sent out, and the first is PIP6060A, which is an ECU code for an oxygen sensor issue. The explanation here is that the engine is receiving incorrect or no information about the exhaust gases coming out. Knowing this bit of data will tell the engine to richen or lean out the fuel mixture, but if a sensor is faulty, the engine can skip a beat or experience premature wear and tear.AdvertisementAdvertisementPIP6060A affects models produced between 2023 and 2026, which are specifically the GMC Sierra and the GMC Canyon. Configurations of the two models that include the 2.7-liter inline-four L3B gasoline engine are affected by this service bulletin.This was published in May 2025, and it instructs technicians to inspect the oxygen sensor after checking for any faults in the torque converter. In addition to checking the condition of the sensor, techs are also supposed to investigate the Lambda readings for any abnormalities or fluctuations.GMCService Bulletin #2The second bulletin is PIP6127, which involves technicians checking the torque converter of the affected models. The bulletin tells dealers how to determine whether a torque converter replacement is necessary.Service bulletin PIP6127 outlines the steps and processes a vehicle is required to go through that will facilitate a transmission replacement. The bulletin also covers models like 2023 to 2026 GMC Canyons, 2019 to 2026 GMC Sierras with the turbocharged 2.7-liter inline four (L3B), and certain units of the Sierra that have the 2.7-liter turbo or the 5.3-liter V8 L84.AdvertisementAdvertisementAccording to the bulletin, technicians are required to inspect and investigate the issue first. For the technicians, they're required to flush the transmission fluid and drive the vehicle for 200 miles. If the shuddering continues, then the dealership will be instructed to call the company's Product Quality Center to order a new transmission unit, but not before a proper diagnostic process is completed.GMCThis story was originally published by Autoblog on Aug 31, 2026, where it first appeared in the News section. Add Autoblog as a Preferred Source by clicking here.
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