This intake manifold gasket seals the joint between the intake manifold and the cylinder head, preventing unmetered air from entering the engine. It sits between the two mating faces and compresses under fastener torque to create a gas-tight seal. A failed gasket allows air leakage, which leans the air-fuel mixture and can cause rough idle, reduced power, or diagnostic trouble codes. The gasket is constructed from a material selected to resist the temperature cycling and oil exposure present in the intake tract. On installation, ensure both sealing surfaces are clean and flat, and tighten the manifold fasteners to the specified torque in the correct sequence.