General Motors is still working on a fix for shuddering eight-speed automatic transmissions in the GMC Sierra and GMC Canyon, with the issue affecting certain 2023 to 2026 model-year vehicles. Owners have reported “a surge or shudder” while driving on the highway under light throttle, while GM has issued service bulletins but has not filed a recall notice at the time of writing.

GM Service Bulletin Addresses Oxygen Sensor Issue

The first bulletin, PIP6060A, is an ECU code related to an oxygen sensor issue. The problem involves the engine receiving incorrect or no information about the exhaust gases coming out.

This information helps the engine richen or lean out the fuel mixture. If the sensor is faulty, however, the engine can skip a beat or experience premature wear and tear.

PIP6060A affects 2023 to 2026 GMC Sierra and GMC Canyon models equipped with the 2.7-liter inline-four L3B gasoline engine. The bulletin was published in May 2025.

Under the bulletin, technicians are instructed to inspect the oxygen sensor after checking for any faults in the torque converter. They are also required to investigate Lambda readings for any abnormalities or fluctuations.

Second Bulletin Focuses on the Torque Converter

GM’s second bulletin, PIP6127, involves checking the torque converter on affected vehicles. It provides dealers with procedures for determining whether the torque converter needs to be replaced.

The bulletin outlines the steps and processes a vehicle must go through before a transmission replacement can be ordered. It covers 2023 to 2026 GMC Canyon models, 2019 to 2026 GMC Sierra models with the turbocharged 2.7-liter inline-four L3B, and certain Sierra units equipped with the 2.7-liter turbo or 5.3-liter V8 L84.

Dealers Must Complete a Diagnostic Process

According to PIP6127, technicians must first inspect and investigate the issue. The process requires technicians to flush the transmission fluid and then drive the vehicle for 200 miles.

If the shuddering continues after that process, the dealership will be instructed to contact GM’s Product Quality Center to order a new transmission unit. The replacement, however, is not authorized until the proper diagnostic process has been completed.

For now, GM’s service bulletins address the reported transmission and related issues affecting certain Sierra and Canyon models, while no recall notice has been filed at the time of writing.