General Motors has issued a service solution to address an unusual ticking noise in the engines of certain Cadillac models. The technical notice, published in service bulletin PIP6101A, applies to 2025–2026 model-year vehicles equipped with the turbocharged 2.0L I4 LSY engine. This includes the Cadillac CT4, CT5, XT4, XT5, and XT6.

According to service documentation, a noticeable ticking sound can emerge from the upper section of the engine, traced to components within the valve train. GM engineers determined that contamination particles entering the hydraulic valve lash adjusters could be the cause. When debris infiltrates the mechanism, an adjuster may fail to maintain proper oil pressure. This leads to partial compression, increased valve train clearance, and the resulting characteristic noise.

The bulletin specifies that technicians should first confirm the noise source, such as with a stethoscope, before proceeding. After removing the camshaft housing, they inspect the rocker arms and lash adjusters. If even one faulty component is found, the service instruction mandates replacing all 16 hydraulic lash adjusters and all 16 rocker arms. This approach aims to prevent the issue from recurring.

Document PIP6101A expands on GM's earlier recommendations, now covering a broader range of models with the LSY engine. Owners experiencing such noises are advised to contact their dealer. Service bulletins like this help swiftly identify and resolve technical issues, even in newer vehicles like those from the 2026 model year.