BMW 4 Series Exhaust System: Specs, Fitment & Common Faults
On the 4 Series, related engines can genuinely automatically sense when a regen is needed and raise the exhaust temperature themselves.
Illustration for editorial purposes
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OEM Part Number: confirm via VIN — Rear silencer (aftermarket) Bosal 247-413 / Walker 05924
| Rear silencer (back box) — aftermarket | Bosal 247-413, 247-037, 247-981 (need accessories); Walker 05924 (1170 mm, code 53, filled); Ernst 251006; MTS 01.60519 (580 mm); Vegaz BS-451 (999 mm), BS-83, BS-85, BS-380 (580 mm), BS-223EBER (990 mm), BS-260EBER (975 mm), BS-154IMA (1130 mm); Polmo 03.28, 03.07 (without cat), 03.67 |
|---|---|
| Centre / intermediate silencer — aftermarket | No Bosal/Walker/MTS; Vegaz BS-140 (670 mm), BS-134, BS-136, BS-294IMA (950 mm), BS-295EBER; Polmo 03.63 (without cat), 03.51, 03.65, 03.123; Ernst 275002/275040 (750 mm repair solutions); 4MAX 0219-01-00318P (rear, 1160 mm) |
| Front pipe / catalytic converter (DPF on diesels) — aftermarket | or DPF: Bosal 090-261 (Euro 6), 090-201 (Euro 4/5), both ECE with fitting parts; Walker 20712 (1200 mm, 4.8 kg, code 91, with fitting parts); JMJ 1279 (SCR, Euro 5/6), 1080254 (720 mm); Vegaz BK-300, BK-304, BK-308, BK-893; BM Catalysts BM92464H (Euro 5), BM92283H, BM92585H (Euro 6); AS 45310 (560 mm, Euro 6, OBD), 45298 (440 mm), 45290 (Euro 4/5) |
| Genuine (OE) numbers quoted | None quoted in catalogue listings — order genuine parts against your VIN |
| Fitment notes | Engines (e.g. 420d 184 HP) listed without part mapping; no twin-exit info. |
BMW 4 Series Exhaust System: The Part That Announces Its Own Problems
On the BMW 4 Series, sound is usually the first clue here, ahead of any visual sign — a rattle, a drone, noise that's crept in gradually or arrived overnight. It's one of the more forgiving faults in that sense, since your ears will likely flag it before it becomes a bigger problem.
BMW 4 Series Exhaust System: What It Does
The BMW 4 Series's exhaust system handles three things at once: clearing burnt gases from the engine, cutting noise via the silencer, and treating emissions through a catalytic converter and particulate filter. Because petrol and diesel emissions requirements differ, it often uses genuinely different exhaust systems depending on engine type.
BMW 4 Series Exhaust System: Watch: Replacing It
Covers F32 428i; swaps in a different rear exhaust.
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A Genuinely Useful Piece of Context Worth Knowing About DPF Regeneration — BMW 4 Series Exhaust System
If you're worried about the DPF on this diesel, this is genuinely useful to know: related BMW engines can genuinely sense when the DPF needs to regenerate and will automatically raise the exhaust temperature during normal driving, without needing sport mode manually selected.
It's also genuinely worth knowing that if your regular driving is mostly short journeys, giving the car a proper, sustained run at higher revs for around 20 to 30 minutes every six to eight weeks can help ensure the DPF gets a genuine opportunity to regenerate fully.
BMW 4 Series Exhaust System: 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 BMW Exhaust System
The same part, covered across other BMW models.