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, Subaru FSM specs are modest (intake bolts are light, exhaust nuts moderate), and over‑tightening can warp flanges or strip studs. After an exhaust-gasket job, check for soot traces after a few heat cycles. On turbo models (WRX/STI), there are extra gasketed joints around the up‑pipe and downpipe, renew them whenever the system is apart.

• Best practice: replace gaskets whenever manifolds come off.
• Listen for ticks or hisses, watch trims and fuel economy.
• Use correct torque and sequence per the Subaru FSM.

References: Subaru Factory Service Manual, MY2009 Impreza (Intake/Exhaust sections), Subaru FAST EPC listings for intake and exhaust manifold gaskets for 2009 Impreza variants.

Popular questions about 2009 Subaru Impreza manifold gaskets

Does a 2009 Impreza have separate intake and exhaust manifold gaskets?
Yes. The platform uses dedicated intake-manifold gaskets at the heads and exhaust-manifold gaskets at the header-to-head flanges. Turbo variants add more gasketed joints in the hot side. They’re service parts and should be renewed whenever the manifolds are removed.

How often should manifold gaskets be replaced?
There’s no fixed kilometre interval. Replace them proactively any time a manifold is off, and reactively if symptoms appear—hiss or whistle, tick on acceleration, lean codes, or soot at the flange. Age, heat cycles, and corrosion can all flatten or harden the gaskets over time.

Can a leaking manifold gasket damage the engine?
It can. An intake leak makes the engine run lean and rough, increasing combustion temps. An exhaust leak pre‑O2 sensor skews fuelling and can burn nearby components. Fixing leaks early keeps the Impreza running sweet and within emissions targets.