420d / 430d (B47 / N47 / B57 diesel)
2013–2024 · diesel · 1995cc · 190hp
Engine codes: B47, N47, B57
Reliability, common problems and owner reviews for the Bmw 4 Series 420d / 430d (B47 / N47 / B57 diesel). Check this before you buy used.
The diesels span the early 2.0 N47 (F32 — carries the notorious rear-mounted-timing-chain wear that's labour-heavy to fix) and the later 2.0 B47 (the much-improved replacement, shared with the 3/5-Series and X-models), plus the smooth 3.0 straight-six B57/N57 (430d). The B47 is the one to buy: it fixed the N47's chain reputation. Standard modern-diesel cautions remain: DPF and EGR on short trips (EGR cooler a known weak point), injector attention, and AdBlue on later cars. The straight-six 430d is a superb, durable long-distance engine. Buy on chain (avoid a rattly N47), EGR and DPF history.
Same engine, other cars
This is the same physical engine (N47) sold under different names across brands. Reliability is broadly shared — cross-check these:
- BMW 3 Series E90— 320d 2.0d (M47TU2, early)163hp
- BMW 2 Series— 216d / 218d / 220d (B37 / B47 diesel)190hp
- BMW 3 Series F30— 316d / 318d / 320d (N47 → B47)190hp
- BMW 3 Series G20— 318d / 320d / 330d (B47 / B57 diesel)190hp
- BMW 5 Series E60— 520d 2.0d (M47 → N47)177hp
- BMW X3— 2.0d (M47 / N47)177hp
- BMW X2— sDrive18d / 20d / xDrive20d (B47)190hp
- BMW X3— xDrive20d (N47)184hp
- BMW 1 Series E87— 116d / 118d / 120d (N47, 2007–2011)177hp
- BMW 5 Series G30— 520d / 530d / 540d (B47 / B57 diesel)190hp
- BMW 3 Series E90— 318d / 320d 2.0d (N47)177hp
- BMW X3 G01— xDrive20d / 30d (B47 / B57 diesel)190hp
- BMW X1— 18d / 20d / 23d (N47 diesel)184hp
Known Issues
Early N47 rear-mounted chain wears → rattle → labour-heavy fix. B47 resolved this.
Fix / Workaround: Prefer B47; on N47 listen for cold-start rattle (walk away if present).
Repair cost: €800–€2500
Typically appears after: 120,000 km
EGR cooler weak point; DPF clogs on short trips; AdBlue on later cars.
Fix / Workaround: Replace EGR cooler; motorway regens; diagnose SCR.
Repair cost: €300–€1200
Typically appears after: 130,000 km
Year Cutoffs
Mileage Thresholds
After 220,000 km: B47/B57 high-mileage capable.
Pre-Purchase Checklist
- ☐Prefer B47 over early N47
- ☐N47: cold-start rattle = walk away
- ☐430d straight-six is superb
Frequently asked questions
Is the Bmw 4 Series 420d / 430d (B47 / N47 / B57 diesel) reliable?
Maint. Sensitive — The diesels span the early 2.0 N47 (F32 — carries the notorious rear-mounted-timing-chain wear that's labour-heavy to fix) and the later 2.0 B47 (the much-improved replacement, shared with the 3/5-Series and X-models), plus the smooth 3.0 straight-six B57/N57 (430d). The B47 is the one to buy: it fixed the N47's chain reputation. Standard modern-diesel cautions remain: DPF and EGR on short trips (EGR cooler a known weak point), injector attention, and AdBlue on later cars. The straight-six 430d is a superb, durable long-distance engine. Buy on chain (avoid a rattly N47), EGR and DPF history.
What are the common problems and reviews for the Bmw 4 Series 420d / 430d (B47 / N47 / B57 diesel)?
The most commonly reported problems: N47 rear timing chain (early), EGR cooler / DPF / AdBlue.
Is a used Bmw 4 Series 420d / 430d (B47 / N47 / B57 diesel) worth buying?
Fine if serviced correctly — but it punishes neglect hard. History and the right consumables matter.