4 Series
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Which Bmw 4 Series engine is the most reliable? See common problems, reviews and reliability verdicts across generations and engines.
Frequently asked questions
Which Bmw 4 Series engine is the most reliable?
216d / 218d / 220d (B37 / B47 diesel) — Maint. Sensitive verdict. The diesels are the high-mileage G20 choice — the 2.0 B47 (320d, often mild-hybrid — the robust engine that long ago replaced the chain-troubled N47) and the superb 3.0 straight-six B57 (330d). Both are strong, exceptionally economical and well-matched to the executive saloon/estate. Standard modern-diesel cautions: DPF and EGR on short trips (EGR cooler a known weak point), injector attention, twin-dosing AdBlue/SCR, and timing-chain checks at very high miles. The 330d straight-six is one of the best long-distance engines you can buy. A motorway-driven, serviced car is a genuine 300k long-hauler. Buy on EGR, DPF and AdBlue history.
Which Bmw 4 Series engines should you avoid?
None of the Bmw 4 Series engines listed are rated "Problematic" or "Avoid" — but always check the service history before buying.
What are the most common Bmw 4 Series problems?
The most commonly reported problems across all Bmw 4 Series generations and engines: N47 timing-chain failure (rear, pre-~2015), N47 rear timing chain (early), EGR cooler / DPF, Timing chain / injector (high miles), EGR cooler / DPF / AdBlue.