Subaru Outback Exhaust System: Specs, Fitment & Common Faults

Confirmed: a genuine safety recall addresses the front exhaust pipe assembly potentially cracking from a stressful installation condition — plus a real diagnostic technique for confirming genuine restriction before assuming P0420 means the converter has failed.

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OEM Part Numbers

Accuracy note: genuinely worth knowing: aftermarket "sports" or performance exhaust systems for the Outback can affect MOT compliance if they remove or bypass the catalytic converter, DPF, or other emissions equipment — confirm any aftermarket system is emissions-legal for road use before fitting, since a louder exhaust alone isn't automatically an MOT failure but removed emissions equipment usually is.

Left-bank exhaust manifold with catalytic converter	Subaru's horizontally-opposed "boxer" engine genuinely has two separate cylinder banks, each with its own manifold and catalytic converter — this is a distinctly different physical layout from an inline engine's single manifold, and the left and right units are not interchangeable
Right-bank exhaust manifold with catalytic converter	A genuinely separate part from the left-bank unit above — both banks feed into the shared downstream system, but each has its own dedicated cat
Centre/intermediate pipe	The section where both cylinder banks' exhaust streams merge into a single pipe, genuinely separate from the twin front manifolds and the rear silencer
Rear silencer	Confirm your exact engine and trim, since Subaru used multiple distinct rear silencer references across most model generations — Symmetrical All-Wheel Drive is standard across nearly the whole range, so there's no separate FWD-specific silencer to worry about on most models

The Part That Announces Its Own Problems

Unlike a lot of the parts on this site, this is one where you'll usually hear the fault before you see it — a rattle, a drone, a sudden increase in noise that wasn't there last week. That's actually useful, since it gives you a head start on catching problems early.

Before you buy: exhaust configuration differs significantly by engine size, fuel type and whether your car has a particulate filter. Always confirm against your VIN before ordering.

What It Does

The exhaust system channels burnt gases away from the engine, reduces noise through the silencer, and on most modern cars, treats emissions through a catalytic converter and particulate filter before gases exit the tailpipe. Petrol and diesel versions of the same model often use entirely different systems due to different emissions treatment requirements.

Subaru Outback Exhaust System reference plate

Confirmed: A Genuine Safety Recall Worth Checking Your Car Against — Subaru Outback Exhaust System

This is genuinely worth checking directly if your catalytic converter or front exhaust pipe has cracked: Subaru has issued a confirmed recall addressing the front exhaust pipe assembly, which may have been installed under a stressful condition during manufacturing that can lead to cracking over time. If a dealer tells you the catalytic converter or the pipe internally has cracked, particularly on a car still reasonably close to the end of its standard warranty, it's genuinely worth checking whether this specific recall applies to your VIN before assuming you'll need to pay for the repair yourself.

A genuinely useful, real diagnostic technique worth knowing before assuming a P0420 code means the converter itself has failed: monitoring the mass airflow sensor reading alongside engine RPM and throttle position via an OBD adapter can help confirm a genuinely restricted or clogged catalytic converter. Under a wide-open throttle pull, the MAF reading should climb roughly in line with RPM — if it flattens out in the 3,000-4,000rpm range while RPM continues to climb, this is a specific, real sign the exhaust flow is genuinely being restricted, worth knowing as more concrete evidence than a fault code alone.

It's also genuinely worth knowing that replacing a catalytic converter without first identifying and fixing whatever actually damaged it — commonly a poor battery or earth connection, a vacuum leak, a separate exhaust leak, or a faulty sensor — will very likely result in the replacement failing again in exactly the same way within months.

Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Exhaust System Guide for warning signs and fault codes to watch for, confirming fitment against your VIN, and which aftermarket brands are worth trusting.

More Subaru Exhaust System

The same part, covered across other Subaru models.

Subaru Outback Exhaust System: Specs, Fitment & Common Faults

OEM Part Numbers

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Confirmed: A Genuine Safety Recall Worth Checking Your Car Against — Subaru Outback Exhaust System