Parts for your 2009 Subaru Impreza-Manifold gasket

2009 Subaru Impreza manifold gasket — what it does and when to replace it

A manifold gasket absolutely is used on the 2009 Subaru Impreza. The Subaru Factory Service Manual (MY2009 Impreza, Intake [IM] and Exhaust [EM] sections) specifies intake-manifold gaskets between the manifold and each cylinder head, and exhaust-manifold gaskets between the headers and the heads. The Subaru FAST electronic parts catalogue lists these gaskets as dedicated service parts for both non-turbo and WRX/STI turbo variants, confirming they’re standard fitment on the platform.

On this Impreza, manifold gaskets do a quiet but vital job. Intake-manifold gaskets keep unmetered air from sneaking into the engine, so fuelling and idle stay steady and the ECU can trim correctly. Exhaust-manifold gaskets seal hot gas at the ports, helping the oxygen sensors read cleanly, keeping noise down, and protecting nearby components from heat and soot. When they’re sealing properly, the car runs smoother, uses less fuel, and meets emissions targets.

They’re considered single‑use crush gaskets, so any time an intake or exhaust manifold is removed, fresh gaskets should be fitted. Typical warning signs are a whistling or hissing on cold start (intake), a sharp ticking that gets louder under load (exhaust), rough idle, lean codes (like P0171), high positive fuel trims, or exhaust smell in the engine bay. Left alone, leaks can burn valves, skew O2 readings, and dent performance.

For servicing, a careful clean of mating faces is key—no gouging or deep scraping. Fit new OEM‑quality gaskets dry unless the Subaru manual calls for a specific sealant on a particular joint. Torque fasteners evenly in the factory sequence