Parts for your 2021 Subaru Impreza-Exhaust gasket

2021 Subaru Impreza Exhaust Gasket: What It Does and When To Replace It

Yes, the 2021 Subaru Impreza uses exhaust gaskets. This is confirmed by Subaru’s factory Service Manual for the FB20-powered Impreza (Exhaust section) and the Subaru FAST electronic parts catalogue, which both show multiple gasket points: at the cylinder head to exhaust manifold (manifold-with-catalyst), the spring-bolt “donut” at the front pipe, and flat flange gaskets further down the system. So an exhaust-gasket is absolutely relevant on this model.

On the 2021 Impreza, exhaust gaskets seal hot gases as they leave the engine, keeping things quiet, efficient, and safe. They live at key joints where metal parts meet and expand/contract with heat. Up front, multi-layer steel gaskets sit between the cylinder head and the manifold-catalyst assembly. A crush-style “donut” gasket seals the spring-jointed connection to the front pipe, and flat gaskets are used at the centre and rear flanges. It’s all designed so the car breathes freely without leaks, pops, or fumes sneaking into the cabin.

During routine servicing, exhaust gaskets aren’t a scheduled replacement item, but they should be checked whenever the car is on the hoist. Any time a joint is undone—say for clutch work, O2 sensor replacement, or a new muffler—plan on fitting new gaskets. Reusing old ones usually leads to leaks and comeback jobs.

• Common leak clues: a ticking sound on cold start, sooty markings around a flange, whiffs of exhaust near the engine bay, or a sudden change in fuel use or engine note.
• Best practice: replace disturbed gaskets as a set, especially the front “donut” and its spring bolts, and torque hardware to the service manual spec in the proper sequence.

A few handy tips the workshop crowd swear by: don’t use sealant on exhaust gaskets—they’re designed to seal dry. If studs are corroded, replace them rather than forcing them, it saves knuckles and call-backs. Only use anti-seize on sensor threads where specified, not on gasket faces. And always check engine and exhaust hangers, excessive movement makes even fresh gaskets leak.

Referencing: Subaru Impreza (GK/GT) 2017–2021 Service Manual, Exhaust section, Subaru STIS technical data, and Subaru FAST/EPC listings for FB20 exhaust assemblies all document the gasket locations and replacement guidance noted above.

Popular questions about 2021 Subaru Impreza exhaust gaskets

How long do the exhaust gaskets typically last?
On a well-maintained Impreza, factory gaskets can last many years. They’re usually replaced when the joint is opened or if there’s a leak. Heat cycles, corrosion, or a knock to the system can shorten their life, so inspection at each service is smart.

Can a leaking exhaust gasket damage the engine?
Upstream leaks can skew O2 sensor readings and make the engine run off, costing fuel and performance. If ignored, hot gas blow-by can also erode flanges or studs, turning a quick fix into a bigger repair. Best to sort it early.

Should sealant be used with a new exhaust gasket?
No. The Impreza’s exhaust gaskets are designed to seal on their own when torqued correctly. Adding sealant can cause improper seating, contamination, or burn-off that leads to leaks.