Parts for your 2006 Subaru Impreza-Manifold gasket

2006 Subaru Impreza manifold-gasket — what it is and why it matters

Yes, a manifold-gasket is absolutely used on the 2006 Subaru Impreza. The Subaru Factory Service Manual for the 2006MY Impreza (engine intake and exhaust sections) and the Subaru FAST electronic parts catalogue both specify intake manifold gaskets and exhaust manifold gaskets for the EJ253 (2.5i) and the turbo EJ255/EJ257 (WRX/STI). Major aftermarket catalogues for this model also list these gaskets as standard service parts, so the part is relevant to every 2006 Impreza variant.

The manifold-gasket’s job is simple but crucial. On the intake side, a pair of gaskets seals the intake manifold to the cylinder heads, keeping unmetered air out so the ECU can control the air–fuel mix properly. On the exhaust side, gaskets seal the exhaust manifold (headers) to the heads so hot gases don’t escape under the bonnet and throw off O2 sensor readings. When these seals fail, owners can cop rough idle, hunting revs, lean mixture fault codes, a tell-tale tick on cold start, or that sharp exhaust pong in the engine bay.

There’s no set kilometre interval for replacement in the manuals. Instead, Subaru specifies new gaskets any time the manifold is removed, and replacement whenever a leak is found. For a 2006 Impreza, that means fitting fresh intake and exhaust manifold gaskets during major top-end work, inlet removal for injector or TGV service, or any exhaust repairs. Use quality OE or reputable aftermarket gaskets, clean mating faces thoroughly, and follow the FSM tightening sequence and torque specs. Avoid silicone sealants on these joints — a proper composite or multi-layer steel gasket does the sealing.

Handy signs it’s time to act include:

• Hiss or whistle from the intake area, rough idle, or a lean code.
• Ticking from the exhaust ports on cold start, soot marks at the flange, or exhaust smell under the bonnet.

On higher-kilometre cars or turbo WRX/STI models that see more heat, it’s smart preventative maintenance to refresh manifold gaskets when nearby work is already happening. Inspect studs and nuts, replace any crusty hardware, and check heat shields. For WOF/regos, remember that any exhaust leak ahead of the catalytic converter can be a fail, so don’t ignore that tick.

DIY-capable owners can handle the intake side with patience and the right tools, the exhaust side often needs penetrating oil, careful stud work, and a torque wrench. When in doubt, leave seized hardware to a trusted mechanic to avoid snapped studs.

Popular questions about the 2006 Subaru Impreza manifold-gasket

How often should manifold gaskets be replaced on a 2006 Impreza?
There’s no fixed schedule. Replace them whenever the intake or exhaust manifold is removed, or if there are symptoms of a leak. Many last well past 150,000 km, but heat cycles, turbo setups, and past work quality make a big difference.

What are the common symptoms of a failing manifold-gasket?
For intake leaks: hissing, unstable idle, poor fuel economy, and a lean mixture fault. For exhaust leaks: a ticking noise on cold start that softens when warm, faint exhaust smell under the bonnet, or soot traces near the manifold flange.

Can a home mechanic replace the manifold-gasket on a 2006 Impreza?
Yes, with the right tools and a service guide. The intake side is moderate difficulty, label hoses and follow the tightening sequence. The exhaust side can be trickier due to heat shields and seized fasteners, especially on turbo models. If studs look dodgy, it’s worth handing it to a pro.