Engine Ticking Issue Now Linked to Several GM Models

The Scope Widens

General Motors has updated service bulletin PIP6101, which addresses an engine ticking noise caused by a manufacturing defect. The revised version, PIP6101A, now includes more 2025–2026 models equipped with the 2.0-liter inline-four LSY turbocharged engine, in addition to the previously listed 2.5-liter LK0 and 2.7-liter L3B power units.

This means owners of the Buick Envision, Chevrolet Blazer, and Cadillac CT4, CT5, XT4, XT5, and XT6 may now be affected by the issue. The LSY debuted for the 2019 model year and typically serves as the base engine in these models. However, as noted, the ticking noise is not necessarily an engine design issue, but rather the result of a manufacturing defect. This is also a service bulletin, meaning it is sent by GM to dealers rather than directly to owners, as would typically be the case with a recall.

What’s Happening Under the Valve Cover

The issue stems from manufacturing debris entering the hydraulic valve lash adjuster, preventing the component from pumping oil properly and resulting in a “soft” adjuster. Without proper hydraulic pressure, the affected engines may produce a ticking noise. Dealers are instructed to use a stethoscope or other methods to inspect the valvetrain first. If technicians find any soft adjusters, all 16 hydraulic valve lash adjusters and 16 valve rocker arms must be replaced.

GM said the repair falls under the vehicles’ powertrain warranty coverage.

For reference, other models that use either the 2.5-liter LK0 or 2.7-liter L3B include the Buick Enclave, Chevrolet Colorado, Traverse, and Silverado 1500, as well as the GMC Acadia, Canyon, and Sierra 1500. The updated service bulletin does not identify a safety risk related to the ticking noise. However, if left unaddressed, it could lead to long-term valvetrain wear while leaving some owners dealing with persistent noise.

A Problem on the Production Line

The newly added 2.0-liter LSY is assembled at GM’s Spring Hill plant in Tennessee, though the affected Envision itself is produced in China. In the Cadillac CT5, the LSY can deliver up to 237 horsepower. The two larger engines are also reportedly assembled at the same facility, which could help explain why all three are linked to the same issue.

Because GM did not identify a specific VIN range, owners of affected models may want to have their vehicles checked if they notice the ticking noise.