BMW B47 Engine Reliability Guide
The B47 is BMW's 2.0-litre four-cylinder diesel that replaced the N47 in 2014 and is still in production today. It's the engine you'll find in most recent used 318d/320d/520d/X1/X3 diesels and — crucially — it is ULEZ-compliant (Euro 6). The big thing to verify on any used example is whether the EGR-cooler fire-risk recall (NSC R/2018/151) has been completed.
Quick verdict
The B47 is a sensible buy for UK diesel users who need ULEZ compliance. Significantly more reliable than the N47 it replaces — the timing-chain issue is largely resolved on post-2017 builds. With the EGR recall completed and documented servicing, 200,000+ miles is realistic. Verify the recall paperwork before parting with money.
What is the BMW B47?
Most B47 cars in UK classifieds are 2017+ F-series and G-series models — high proportion of ex-company-car stock with fleet service history. That's good (regular services) and bad (relentless motorway miles, some with questionable cold-start care). AdBlue/SCR glitches are the second-most-common buyer concern after the recall. If the recall is outstanding, it's free work at any BMW dealer — book it before you collect.
| Full engine code | B47D20 |
|---|---|
| Configuration | I4 turbo diesel, common-rail, aluminium block |
| Production years | 2014-present |
| Applicable chassis | F20, F21, F22, F23, F30, F31, F32, F33, F34, F36, F10, F11, F48, F39, F25, G20, G21, G22, G23, G26, G30, G31, G60, G61, G01, G02, G05, U11 |
| Badge names | 116d, 118d, 120d, 218d, 220d, 318d, 320d, 418d, 420d, 520d, X1 18d, X1 20d, X2 20d, X3 20d, X4 20d, X5 25d |
| Real-world UK MPG | 48–58 mpg combined, 55–65 mpg motorway |
| Emissions / ULEZ | Euro 6, ULEZ-compliant |
| Successor | — |
| Reliability score | 6 / 10 (Bimmer.AI internal) |
Common problems
Every failure mode below is based on UK DVSA/recall data, BMW press archives, and observed patterns across independent specialist maintenance schedules. Cost ranges are indicative UK figures.
| Failure mode | Severity | Frequency | Typical onset | UK repair range |
|---|---|---|---|---|
| EGR cooler fire-risk recall (NSC R/2018/151) | Serious | Very common | 40–150k mi | Free (recall) or up to £1,100 |
| Timing chain (early B47, 2014-2016) | Moderate | Uncommon | 80–140k mi | £1,500–£2,500 |
| DPF regen failure | Moderate | Common | 50–120k mi | £400–£1,500 |
| AdBlue / SCR system fault | Moderate | Common | 40–100k mi | £300–£1,200 |
| Swirl flap failure (carried over from N47/M47) | Catastrophic | Uncommon | 100–180k mi | £200–£400 |
EGR cooler fire-risk recall (NSC R/2018/151)
- Unexplained coolant loss
- White smoke from exhaust when warm
- Sweet smell from exhaust
- In rare cases: smoke from engine bay or ignition fire
What to do about it: CHECK RECALL STATUS at gov.uk/check-vehicle-recall using the VIN. BMW completed the remedy free of charge on most affected cars. If outstanding, book at any BMW dealer.
If ignored: Engine fire (rare but documented) or hydrolocked engine. £4,000+ replacement.
UK repair exposure: Up to £1,100 (free under recall if applicable).
Recall / TSB: DVSA recall NSC R/2018/151 covers ~320,000 UK vehicles with N47/B47 engines.
Additional notes: If a used car claims 'recall completed', insist on dealer paperwork.
Timing chain (early B47, 2014-2016)
- Mild rattle on cold start
- P0016/P0017 cam-crank correlation codes
What to do about it: Listen on cold start during viewing. Post-2017 rarely affected.
If ignored: Engine destruction.
UK repair exposure: £1,500–£2,500.
Additional notes: Significantly less common than on N47.
DPF regen failure
- DPF warning light
- Limp mode
- Failed MOT on emissions
What to do about it: Motorway driving 30+ min weekly. Avoid school-run-only use.
If ignored: Cracked DPF: £1,500-£2,500 to replace.
UK repair exposure: £400–£1,500.
AdBlue / SCR system fault
- 'X miles to restricted start' warning
- AdBlue level / quality warning
- NOx sensor warning light
What to do about it: Sealed AdBlue only. Top up promptly.
If ignored: Refusal to start (EU regulation, not a fault).
UK repair exposure: £300–£1,200.
Additional notes: NOx sensor £300-500. SCR pump £600-1,200.
Swirl flap failure (carried over from N47/M47)
- Sudden power loss
- Misfire / rough running
What to do about it: Indie can blank-plate the flaps preventatively, £200-400.
If ignored: Ingested flap → bent valves → £4,000+ engine work.
UK repair exposure: £200–£400.
Additional notes: Less common than on N47.
Preventative maintenance schedule
UK independent specialist consensus — typically more cautious than BMW's factory service intervals, especially around oil and timing components.
| Task | Interval | Typical cost | Fix |
|---|---|---|---|
| Engine oil + filter (BMW LL-04) Independent specialist consensus. | Every 10,000 mi | £90–£140 | DIY |
| Fuel filter | Every 30,000 mi | £60–£110 | DIY |
| Air filter | Every 30,000 mi | £25–£50 | DIY |
| AdBlue top-up Sealed AdBlue only. | Every 10,000 mi | £15–£30 | DIY |
| Coolant | Every 60,000 mi | £120–£180 | Specialist |
| Brake fluid | Every 24,000 mi | £60–£100 | Specialist |
| DPF forced regen / cleaning | Every 60,000 mi | £80–£250 | Specialist |
| EGR recall verification (NSC R/2018/151) FREE at any BMW dealer. | ASAP | Free | Specialist |
Long-term verdict
Significantly more reliable than the N47 it replaces. The timing chain issue is largely resolved on post-2017 builds. The remaining concern is the EGR cooler fire-risk recall (NSC R/2018/151) — verify it has been completed on any used purchase. With that done and a documented service history, a well-maintained B47 can realistically do 200,000+ miles. A sensible buy for UK diesel users who need ULEZ compliance.
Buy, negotiate, or walk away
Buy
Post-2017 build, EGR recall completed with BMW paperwork, full service history (BMW or known indie), AdBlue warnings not currently present, no cold-start rattle, chain quiet.
Negotiate
EGR recall outstanding (book it — it's free — but factor in collection/return trip). Active AdBlue warnings (£300–£1,200 depending on NOx sensor vs SCR pump). 2014–2016 early B47 with no chain receipts past 100k.
Walk away
Cold-start rattle lasting more than a couple of seconds on an early B47. Swirl-flap debris on borescope. No service history at 100k+ miles. Persistent limp mode despite recent diagnostic work.
Bimmer.AI is designed to help you identify BMW-specific buyer risks before you travel, negotiate, or pay for an inspection. It does not replace a physical inspection by a qualified mechanic, a legal vehicle-history check (e.g. HPI Check), or independent verification of finance, stolen, or write-off status. Repair-cost ranges are indicative UK figures that vary by region, specialist, parts supply, and labour rates.
Check a specific B47 listing
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Run a Bimmer.AI buyer report →Frequently asked questions
Is the BMW B47 engine reliable?
Yes — significantly more reliable than the N47 it replaced. The timing-chain issue is largely resolved on post-2017 builds, and the engine is Euro 6 ULEZ-compliant. The main buyer concern is verifying the EGR-cooler fire-risk recall (NSC R/2018/151) has been completed.
What is the EGR recall NSC R/2018/151 on the B47?
DVSA safety recall covering ~320,000 UK BMWs with N47 and B47 diesels. The EGR cooler could leak coolant into the intake and, in rare cases, cause a fire. BMW completed the remedy free of charge on most affected cars. Check status at gov.uk/check-vehicle-recall using the VIN before you buy.
Is the B47 ULEZ-compliant?
Yes. The B47 is a Euro 6 diesel and is exempt from London's ULEZ charge. This is a meaningful difference vs the N47 (Euro 5, not ULEZ-compliant) and a common reason buyers move from N47 to B47.
Is the B47 prone to the same timing-chain problem as the N47?
Much less so. Early B47s (2014–2016) still had occasional chain stretch, but post-2017 builds are rarely affected. Listen on a cold start during the viewing — any rattle warrants investigation.
How much is AdBlue / SCR repair on a B47?
NOx sensors run £300–£500 fitted; an SCR pump replacement is £600–£1,200. AdBlue quality warnings are usually resolved by a sealed-bottle top-up (£15–£30). If the dashboard is showing a restricted-start warning, resolve before purchase — EU regs prevent the car from starting once the countdown expires.
Which BMWs use the B47 engine?
Most current UK diesels: 118d/120d (F20/F40), 318d/320d (F30/G20), 520d (F10/G30/G60), X1 18d/20d (F48/U11), X3 20d (F25/G01), X4 20d, plus X5 25d variants. Always verify chassis + engine, not just the badge.