BMW's modern diesel versus the engine that defined a generation. One is cheaper and more common; the other is more reliable and refined. Here's the honest verdict based on 2025 UK data.
The B47 wins for most buyers — it's more reliable, cheaper to fix (on average), and free of the N47's catastrophic timing chain failure mode. The N47 is still a viable choice in the used market if you're on a tight budget and find a well-maintained example, but the B47's improvements in reliability and refinement make it the better long-term investment.
Full spec comparison, deep dives, and which to choose for your budget and peace of mind below.
| N47D20C | B47D20A | |
|---|---|---|
| Introduced | 2007 | 2014 |
| Displacement | 2.0L | 2.0L |
| 2025 UK Enquiries | 1,450 [EM-VERIFIED] | 930 [EM-VERIFIED] |
| Recon Supply Cost | £3,200–£5,500 | £2,800–£4,500 |
| R&R Labour | 10–14 hrs | 8–12 hrs |
| Defining Failure | Timing chain stretch (rear) | EGR cooler (recall) |
| Best For | Budget buyers, short-term ownership | Long-term reliability, lower running cost |
The B47 is the better engine for most buyers. It's more reliable, more refined, and cheaper to fix on a probability-weighted basis. The N47's reputation is defined by a single catastrophic failure mode — timing chain stretch — that can write off an otherwise healthy engine. While the N47 is cheaper to buy used, the risk of a £1,800+ chain repair (or £2,500+ for a replacement engine) makes it a gamble. The B47's EGR cooler issue, while real, is far less costly and often covered by recall. If you're buying a used BMW with a diesel four-cylinder, the B47 is the smart, safe choice. That said, if you find a low-mileage N47 with a documented timing chain replacement, it can still be a bargain — but the B47 is the engine we'd recommend without reservation.
The N47 is BMW's 2.0-litre four-cylinder diesel, produced from 2007 to 2014. It was fitted to a vast range of BMW models, including the 1 Series (E87, F20), 3 Series (E90, F30), 5 Series (F10), X1, X3, and many others. It's the most-enquired diesel engine in our 2025 data (1,450 requests [EM-VERIFIED]), reflecting both its popularity and its known issues. The defining failure is timing chain stretch, particularly on the rear-mounted chain, which can cause catastrophic engine damage if not caught early. Symptoms include a cold-start rattle and loss of power. Repair costs range from £650 to £1,800 for the chain alone, and up to £6,500 for a full engine replacement [PATTERN DATA]. Despite this, the N47 is a capable and efficient engine, and with regular oil changes and early detection, many have covered over 150,000 miles. Full specifications and fitment are on our N47 Knowledge Centre.
The B47 is the successor to the N47, introduced in 2014 and still in production today. It's a more modern, refined, and reliable 2.0-litre diesel, with a redesigned timing chain (front-mounted, far less prone to failure) and improved fuel injection. Our data shows 930 enquiries in 2025 [EM-VERIFIED], and it's the preferred choice for buyers seeking long-term reliability. The main documented issue is EGR cooler failure, which can cause coolant leaks and potential fire risk — but this was subject to a BMW recall, and most affected cars have been addressed [PATTERN DATA]. Repair costs are typically £600–£1,200 for the EGR cooler, far less than the N47's chain replacement. The B47 is also quieter, smoother, and more fuel-efficient, making it the superior engine in almost every way. Full specs and fitment are on the B47 Knowledge Centre.
Over a typical five-year ownership period, the B47 is cheaper to own despite a higher purchase price. The N47's lower initial cost is offset by a higher probability of a major repair (£650–£1,800 for chain, or £2,500+ for a replacement engine). The B47's EGR cooler is a £600–£1,200 fix, and it's less likely to fail catastrophically. Additionally, the B47's improved fuel economy (by about 5-10%) and lower servicing costs (fewer oil changes due to better oil degradation) add up. In our probability-weighted analysis, the B47 comes out ahead by roughly £500–£1,000 over five years, even before accounting for peace of mind. Use our ownership cost calculator to run your own numbers.
N47 — cheaper to buy upfront. Just budget for a timing chain inspection and be prepared to walk away if it rattles on cold start.
B47 — the smarter choice. Lower risk of a catastrophic failure, better fuel economy, and more refined driving experience.
B47 — the N47 chain risk makes it a ticking time bomb at high mileage. The B47 is far more robust.
B47 — quieter, smoother, and more responsive. The N47 feels agricultural by comparison.
The decision ultimately comes down to budget and risk tolerance. The N47 can be a bargain if you find a well-maintained example with a documented chain replacement. For most buyers, the B47's reliability and refinement make it worth the extra upfront cost.
Yes, significantly. The B47's timing chain is front-mounted and much less prone to failure. The N47 is known for rear-mounted timing chain stretch, which can be catastrophic. The B47's main issue (EGR cooler) is less severe and often covered by recall.
The B47 is cheaper to replace, at £2,800–£4,500 supply only versus £3,200–£5,500 for the N47, reflecting its lower demand (930 vs 1,450 enquiries) and improved parts availability.
No. If you find a low-mileage N47 with a documented timing chain replacement, it can be a great bargain. Just factor in the risk and budget for a chain inspection before purchase.
The B47 is more fuel-efficient, typically offering 5-10% better real-world MPG due to improved injection technology and lower friction.
Yes, both can suffer from DPF clogging with urban driving. Regular motorway runs are recommended for both. The B47's DPF regeneration is more refined.
Both are available in similar power outputs (150-190 hp). The B47 feels more responsive and smoother in everyday driving.
Real 2025 DataBoth engines analysed from 24,650 UK enquiries.
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