Parts for your 2020 Subaru Impreza-Manifold gasket

2020 Subaru Impreza manifold gasket: what it does and when to replace it

Yes, the 2020 Subaru Impreza uses manifold gaskets. On the FB20 engine there are intake manifold gaskets (one per bank on the boxer layout) and exhaust manifold/header gaskets. This is confirmed by Subaru’s Factory Service Manual for the 2017–2021 Impreza (Engine > Intake/Exhaust sections), the Subaru FAST electronic parts catalogue, and major gasket manufacturers’ application guides for the FB-series engines. So, a manifold-gasket is absolutely relevant to a 2020 Subaru Impreza.

These gaskets seal the mating surfaces between the cylinder heads and the intake or exhaust manifolds. On the intake side they keep unmetered air from sneaking in, preserving correct fuel trims, smooth idle and decent economy. On the exhaust side they prevent hot gas leaks that can cause a ticking sound, fumes under the bonnet, and misleading oxygen sensor readings that upset mixture control.

They’re not a scheduled service item, but they should be replaced any time a manifold is removed—think injector, EGR or intake service, or exhaust work. Always use quality OEM or equivalent gaskets, install them dry unless the workshop manual explicitly calls for a dab of sealant at a corner or joint, and clean the mating faces so they’re oil-free and flat. Tighten fasteners in the sequence and torque values specified in the Subaru service data, working in stages. On exhaust hardware, use new nuts where specified and apply anti-seize to studs as permitted to make future work less of a drama.

Typical signs it’s time to sort a manifold gasket include:

• Hissing, whistling or a hunting idle (intake leak).
• Ticking on cold start, exhaust smell in the cabin or under the bonnet (exhaust leak).
• Lean codes (e.g., P0171), rough running, or higher fuel use.

If an intake gasket is leaking, driving can lead to a lean condition and misfires, an exhaust leak ahead of the front O2 sensor can trick the ECU and harm the cat over time. Best bet is to organise a prompt fix. After intake work, it’s smart to check for vacuum leaks with smoke, clear any stored codes, and verify fuel trims with a scan tool. For exhaust work, recheck fastener torque after a few heat cycles if the manual allows. On this Impreza, there are two intake and two exhaust manifold gaskets due to the flat-four layout—replace them as a set for even sealing.

Popular questions

Does the 2020 Subaru Impreza have both intake and exhaust manifold gaskets?
Yes. The FB20 boxer engine uses two intake manifold gaskets (one per head) and two exhaust/header gaskets. They’re listed in Subaru’s parts catalogue and addressed in the factory service procedures for manifold removal and refit.

Can I keep driving with a leaking manifold gasket?
Not recommended. An intake leak can make the engine run lean and rough, while an exhaust leak ahead of the oxygen sensor can skew fuel control and risk catalytic converter damage. Short trips might be possible, but it’s best to book repair promptly.

Do manifold gaskets need sealant on a 2020 Impreza?
Generally, no—fit them dry. Only apply sealant where the Subaru service manual specifically instructs, usually tiny spots at certain joints. Overusing sealant can squeeze into passages and cause headaches later.