Parts for your 2020 Mitsubishi Asx-Exhaust gasket

2020 Mitsubishi ASX exhaust gasket — what it does and when to replace it

Yes, the 2020 Mitsubishi ASX uses exhaust gaskets. This is confirmed by Mitsubishi Motors’ RVR/ASX service manual (2019–2020 coverage) and the MMC ASA electronic parts catalogue, which show gaskets at the cylinder head to exhaust manifold, the manifold-to-front pipe “donut” joint, and at various flange joints further down the system on both 2.0L 4B11 and 2.4L 4B12 petrol engines.

On a 2020 ASX, the exhaust gasket’s job is simple but critical: keep exhaust gases where they belong. A multi-layer steel (MLS) gasket seals the manifold to the head, coping with big heat cycles and preventing hot gas leaks that can warp components or leave sooty stains. Further back, a crush-style graphite/steel ring (often called a donut gasket) seals the spring-bolted joint to allow a bit of movement without leaking. Some models also use flat flange gaskets near the centre pipe and rear muffler.

Why it matters: a leak upstream of the oxygen sensors can suck fresh air into the pipe, confusing fuel trims, triggering a check engine light, and making the ASX feel doughy off the mark. It can also make a sharp ticking noise on cold start, ramp up cabin fumes, and cause roadworthy/WOF issues in Australia and New Zealand.

During regular servicing, a quick inspection on the hoist goes a long way. Look for dark carbon tracks around joints, listen for a “chuff” or tick at start-up, and check for loose spring bolts or cracked studs. If a joint has been apart—say for a clutch, cat-back, or muffler swap—fit a new gasket. Reusing old ones is false economy, once crushed, they rarely re-seal properly.

Good practice on the ASX includes:

• Use quality MLS or OEM-equivalent gaskets and new spring bolts where specified.
• Clean flanges flat, replace warped or pitted pieces rather than gooping them up.
• Avoid generic sealants unless the factory procedure calls for it, most exhaust joints are dry-fit with the correct gasket.
• Torque to the factory spec and follow the tightening sequence from the Mitsubishi service manual to prevent warping.

If there’s a whistle or rasp on acceleration, a fuel smell after stops, or the ASX throws lean-mixture or catalyst efficiency codes, an exhaust leak is worth ruling out before chasing sensors and ECUs. Kept sealed and tidy, the exhaust gaskets will generally last years, only needing attention when disturbed or when age and heat finally take their toll.

Popular questions about 2020 Mitsubishi ASX exhaust gaskets

What are the signs of a failing exhaust gasket on a 2020 ASX?
Owners often report a ticking or puffing noise on cold start that softens as the metal expands, a hiss or rasp under load, and faint exhaust odour near the engine bay. Visual clues include sooty marks around the manifold or flange joints. The ECU may log fuel trim or catalyst codes if the leak is ahead of the oxygen sensors.

Is it safe to keep driving with an exhaust gasket leak?
Short trips might be manageable, but it’s not ideal. Pre-sensor leaks can skew air–fuel readings, affecting performance and economy, and may damage the catalytic converter over time. There’s also a risk of fumes entering the cabin and potential WOF/roadworthy failures. Best to schedule a repair sooner rather than later.

Do gaskets need replacing when fitting a new muffler or cat-back?
Yes—any time a joint is separated, plan on new gaskets and, where used, new spring bolts. Fresh sealing hardware helps the new system sit square, prevents weeping leaks, and saves a return trip to chase noises or smells.