Parts for your 2018 Subaru Impreza-Exhaust gasket

2018 Subaru Impreza exhaust gasket — purpose, care and when to replace

Technical sources confirm the 2018 Subaru Impreza does use exhaust gaskets. The Subaru Service Manual for 2018MY Impreza (Exhaust section) specifies gasket replacement when joints are disturbed, and Subaru’s FAST electronic parts catalogue lists gaskets at key flange and slip joints in the system. That includes the manifold/header connections and the front pipe to mid/centre section, typically using a crush “donut” style gasket.

On this model, exhaust gaskets seal the high‑temperature, high‑pressure gas path between pipes and flanges so nothing leaks to atmosphere before the mufflers and catalytic converter do their job. A good seal keeps the note civil, protects nearby components from hot gas, and prevents fresh air being drawn into the system, which can upset O2 sensor readings and fuel trims.

For the 2018 Impreza’s FB‑series engine, expect a multi‑layer steel gasket at the head or header interface, and a compressible donut gasket where the front pipe joins the rest of the system with spring‑loaded bolts. They’re not usually a scheduled service item, instead, they’re replaced whenever the joint is taken apart or a leak is found.

Practical advice for owners and workshops: replace any exhaust gasket that’s been disturbed, crushed, or shows sooting. Always install quality OEM‑equivalent parts, clean the mating faces, and follow the Subaru torque and sequence specs. With spring‑bolt donut joints, use new springs and bolts if corrosion or loss of tension is evident.

• Common signs of a leaking exhaust gasket:
  • Ticking or pfft sound on cold start that quietens as it heats up
  • Sharp exhaust note or fumes under the cabin
  • Black sooty marks at the joint
  • Check engine light due to skewed O2 readings (less common)

• Handy tips:
  • Don’t reuse crush or donut gaskets, they’re designed for one‑time compression
  • A dab of anti‑seize on studs/bolt threads is fine, but never on sealing faces
  • After an underbody knock or scrape, inspect the front pipe joints and hangers

If there’s any doubt, a quick inspection during routine servicing can save a lot of hassle — and keep the Impreza compliant for rego/WOF and sounding the way it should.

Popular questions about 2018 Subaru Impreza exhaust gaskets

How long do exhaust gaskets last on a 2018 Subaru Impreza?
They often last many years and kilometres because they aren’t a regular wear item. However, once a joint is undone, the gasket should be replaced. Age, corrosion, or an impact can also trigger leaks that call for new gaskets.

A well‑maintained, untouched system can go well past 100,000 km without issue, but any service that drops the front pipe or cat‑back should budget for fresh gaskets and, if needed, new spring bolts.

Will a leaking exhaust gasket fail a WOF or rego inspection?
Quite possibly. In NZ and Australia, exhaust systems must be free of leaks and excessive noise. A gasket leak can create both, and may allow fumes near the cabin, which is a safety concern.

Fixing the leak generally involves a new gasket and checking bolt tension and hanger alignment so the joint sits square and seals properly.

Can a donut gasket be reused after removing the exhaust?
Not recommended. Donut gaskets rely on a one‑time crush to achieve the seal. Once compressed, they rarely reseal perfectly if reused.

Reinstalling the exhaust with a fresh donut gasket — and healthy springs/bolts — greatly reduces the risk of post‑service leaks and repeat labour.