Technical Service Bulletin 01-002-23 — 2020 MAZDA MAZDA6

Some vehicles may have coolant leaks at the cylinder head around the exhaust manifold (as shown below). There may be cracks at the stud bolt hole or at the outside of the exhaust manifold. Cracks may be caused by: - Deformation of the exhaust manifold during usage causing unexpected force to certain areas of the cylinder head. - Residual stress generated during production in the cylinder head material may be greater than expected. The external force from the exhaust system when driving over bumps may cause unexpected force to certain areas of the cylinder head. To eliminate this concern, the design of the exhaust manifold gasket and the cylinder head has been modified to reduce the force on the cylinder head.