BMW Engine Reliability Guides
Engine-specific buyer intelligence for UK used BMWs. Common faults, mileage danger zones, real UK repair costs, preventative schedules, and a straight buy/negotiate/walk verdict on each engine family.
Why engine code matters
A "520d" can be an N47, B47, N57 or B57 depending on year. These engines have very different reliability profiles and very different UK repair-cost exposures. Matching the right guide to your listing is the difference between a confident buy and an expensive surprise.
Pick your engine
Not sure which engine is fitted?
Start with the BMW chassis × engine codes reference — look up any BMW by year, model, or badge to find the exact engine family. Then come back here for the buyer guide.
Full engine codes (what is printed on the engine cover)
Buyers search the long code from the sticker or the parts catalogue: N47D20, B47D20B, B48A20M0, N57D30. Each page below decodes one full code, its output tiers and which cars got them.
Check a specific BMW listing
Paste any BMW listing, VIN, or reg plate, Bimmer.AI picks the right engine, pulls the right failure patterns, and returns a 30-second buyer report.
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