Citroen C5 Aircross Exhaust System: Specs, Fitment & Common Faults

A genuinely honest fact: the DPF additive never burns off, meaning even excellent driving habits can't prevent an eventual, expected filter service — plus a real warning against illegal DPF deletion.

Illustration for editorial purposes

OEM Part Numbers

Accuracy note: we weren't able to verify a confident Citroen C5 Aircross exhaust system part number at the time of writing. Please confirm the correct part via a Citroen dealer or parts specialist using your VIN.

A Genuinely Important, Honest Fact: Good Driving Habits Alone Won't Prevent Eventual DPF Service

It's worth knowing something distinct from the usual "just drive faster to regenerate" advice: diesel particulate filters on this platform rely on an additive (commonly referred to as Eolys, or cerine) injected into the fuel to help the trapped soot burn at a lower temperature during regeneration. This additive itself, however, never burns off — it accumulates as a genuine ash residue inside the filter permanently, regardless of how well the car has been driven. This means even a diesel driven mostly on motorways with excellent regeneration habits will eventually need the DPF professionally cleaned or replaced simply due to this ash buildup, typically somewhere in the region of 100,000-120,000 miles — this isn't a fault or a sign of poor maintenance, but a genuine, expected part of diesel particulate filter technology that good driving habits alone can't prevent indefinitely.

A genuine warning worth knowing: DPF or EGR "deletion" — physically removing the filter or disabling the EGR system via modified engine software — is illegal in the UK and will cause an automatic MOT failure once detected. It's also worth knowing this kind of modification has been linked in documented cases to increased fuel consumption, accelerated turbo wear from prolonged higher boost, and in some cases genuine safety concerns from altered exhaust gas behaviour. A genuine repair, however expensive it feels in the moment, avoids both the legal exposure and these documented technical risks.

If you're chasing a specific EGR-related fault, real fault codes worth knowing include P0401 (insufficient EGR flow) and P0405 (EGR position sensor signal fault) — worth mentioning to whoever is diagnosing the car, since these point toward different specific parts of the system rather than a generic "EGR problem."

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.

Citroen C5 Aircross Exhaust System reference plate

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.

Fitment & Compatibility

Exhaust systems differ substantially between the petrol, hybrid and plug-in hybrid versions of the C5 Aircross, since the hybrid versions integrate differently with the electric motor's contribution to deceleration. Always confirm the exact part fitted to your specific engine and powertrain combination before ordering. Whether you're sourcing a replacement exhaust system for your Citroen C5 Aircross from a dealer, specialist, or online marketplace, always check compatibility against your registration or VIN before buying.

Common Faults

Symptoms of Failure

Rattling noise, especially on startup — often a loose or corroded heat shield rather than the exhaust pipe itself, though worth checking both.
Noticeably louder engine noise — points to a hole or split somewhere in the pipe or silencer, typically caused by corrosion.
Visible rust or flaking on the underside — a warning sign of corrosion that will eventually lead to a leak if left unaddressed.
Failed emissions test — can point to a failing catalytic converter or particulate filter rather than the pipework itself.

DIY Replacement Difficulty

Replacing a full exhaust system is a moderate-to-difficult DIY job requiring access to raise the car safely and often penetrating oil to free corroded fixings. Catalytic converter and particulate filter replacement usually requires specific diagnostic equipment afterward to reset fault codes, making that portion of the job better suited to a garage. Expect 2–4 hours for a full system on a home ramp, or less at a garage with the right lift access.

OEM vs. Aftermarket

Reputable aftermarket exhaust systems are widely regarded as a safe, cost-effective alternative to OEM parts for the pipework and silencer sections. Catalytic converters and particulate filters are worth sourcing from well-regarded brands specifically, since counterfeit or substandard versions are a common cause of failed emissions tests and check-engine warnings.

More Citroen Exhaust System Guides

The same part, covered across other Citroen models.