Exhaust · 2026
Audi A4 exhaust cost
An exhaust mid-section on a Audi A4 typically costs £123–£428 fitted at a UK independent garage, with a full system around £271–£942. The longitudinal A4 runs twin rear silencers on most trims — roughly doubling back-box parts against a hatchback — and its documented rattle culprit isn't always the exhaust: active exhaust flaps with perished vacuum lines or tired springs are the classic false alarm.
Emissions hardware
Diesels follow the VW Group timeline — DPFs standard on B8-generation common-rail cars. B9 (2015-on) diesels add AdBlue/SCR with a 12-litre tank, and AdBlue system faults generating large bills appear in UK owner threads. Petrols gained particulate filters progressively from 2017.
What's on a Audi A4 exhaust?
Longitudinal layout: downpipe and cat (or cat/DPF) up front, a centre silencer, then splitting to twin rear silencers with twin tailpipes on most trims and quad exits on S line-style systems. Centre and rear sections are separately serviceable — but a corroded back box on twin-box cars can mean two boxes or a combined rear assembly.
Audi A4 exhaust replacement cost
A mid-section — the most common failure point — typically costs £123–£428 fitted at a UK independent garage, and a full system around £271–£942. If several sections are corroded, replacing the lot is often cheaper than doing them one MOT at a time. The catalytic converter is a separate, much pricier part.
Key things to know
- Exhaust flap rattle on B8/B9 cars is the documented false alarm — perished vacuum lines to the flap actuator or a weak internal spring, both far cheaper than the silencer they impersonate.
- Twin rear silencers roughly double back-box parts cost versus a single-box hatchback.
- Corroded silencer hangers letting the box hang and rattle are a documented aging pattern — check hangers before condemning boxes.
- AdBlue tank, heater and injector faults on B9 diesels appear in owner reports with significant bills — an exhaust-adjacent cost worth knowing about.
Good question
Questions Okay gets asked a lot
How much does an exhaust cost for a Audi A4?
+
Expect £123–£428 fitted for the mid-section — the most common failure point on UK cars — and around £271–£942 for a full system (cat-back) at a UK independent garage in 2026. The catalytic converter is a separate, much pricier part and isn't included in these figures. Stainless-steel systems cost more upfront but last three to four times longer than mild steel. Use our cost calculator to adjust for your region.
My Audi A4 rattles at idle — is the exhaust on its way out?
+
Check the flap first. Many A4s carry an active exhaust flap in the rear system, operated by a vacuum actuator, and the documented failure mode is mundane: the vacuum line perishes or the flap's internal spring weakens, letting the plate flutter and rattle — especially at idle and low revs. It sounds exactly like a dying silencer and costs a fraction as much to put right. Corroded hangers letting a box hang loose are the other cheap culprit. A garage should isolate the rattle with the car on the ramp before quoting for silencers — on this model, the rattle frequently isn't the box itself.
How do I know the exhaust is going on a Audi A4?
+
The classic signs: a deepening, louder engine note (blowing from a corroded section or failed joint), rattling over bumps (broken hangers or internal baffles), and a metallic tinkling on start-up. A sudden loud roar usually means a section has let go completely. At the MOT, a leaking exhaust is a failure and surface corrosion is a common advisory — an advisory on an exhaust section usually becomes a failure within a year, so it's worth pricing the work when the advisory appears rather than waiting.
Get a price for your Audi A4
Estimate the exhaust cost for your car and region, then compare quotes from trusted local garages.