BMW 4 Series 420d Engine ReplacementCompare Prices & Get Quotes
Need a replacement engine for your BMW 4 Series 420d- Get quotes today from trusted UK BMW 420d engine specialists and compare prices on reconditioned, rebuilt and used engines for your 420d Coupe, Gran Coupe or Convertible.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £1,800 to £5,500
Used from £1,800 · Reconditioned from £2,800 · Common codes: N47D20C, B47D20A
From £1,800
Tested, bare/short engine
From £2,800
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
Secure enquiry - no spam, no pressure. Genuine quotes only from vetted UK BMW 4 Series 420d specialists.
3 Simple Steps3 Simple Stepsto Finding the Best BMW 4 Series 420d Replacement Engineto Finding the Best BMW 4 Series 420d Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryBMW 4 Series 420d - Engine History & Specs at a Glance
The BMW 420d joined the 4 Series range at launch in 2013 as the entry-level diesel, offering a compelling blend of economy and performance. Over its production run, the 420d underwent a crucial engine change from the N47 to the more robust B47, addressing reliability concerns and meeting tightening emissions standards.
Variant HistoryBMW 4 Series 420d - Engine History & Specs at a Glance
The BMW 420d joined the 4 Series range at launch in 2013 as the entry-level diesel, offering a compelling blend of economy and performance. Over its production run, the 420d underwent a crucial engine change from the N47 to the more robust B47, addressing reliability concerns and meeting tightening emissions standards.
BMW 4 Series 420d
Fuel TypeDiesel
Engine Size Range2.0L (1995cc) consistent across all generations
Power Output Range184-190hp across the variant's historyEngine History Timeline
N47D20C 2.0-litre turbo-diesel, 184hp - original 420d engine for F32/F33/F36 chassis
B47D20A 2.0-litre turbo-diesel, 190hp - Euro 6-compliant successor to the N47, introduced as part of the Life Cycle Impulse (LCI) for the 4 Series range
420d receives 48V mild-hybrid technology as part of the G22 generation launch improving efficiency and low-end response
Key Specs Snapshot
Fuel TypeDieselEngine Size Range2.0L (1995cc) consistent across all generationsPower Output Range184-190hp across the variant's historyYears Produced2013-presentEvery engine fitted to the BMW 4 Series 420d is covered below, with UK rebuilt pricing and known failure points.
BMW 4 Series 420d Engine Codes - Specifications & Replacement CostBMW 4 Series 420d Engine Codes - Specifications & Replacement Cost
2.0L Diesel (2013-2015)
Power Output184hpYears Fitted2013-2015
Compatible Trim Levels
- 420d
- 420d M Sport
- 420d Luxury
- 420d xDrive (four-wheel drive adds ~1hr to fitting labour)
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,800-£3,200【EM-QUOTE】
Reconditioned
Addressed known issues, tested
£3,200-£5,500【EM-QUOTE】
Rebuilt
Full teardown, upgraded internals
£4,500-£6,500【EM-QUOTE】
Common Failure
Timing chain stretch and tensioner failure (rear-mounted chain design). Early warning: cold-start rattle from the rear of the engine. Catastrophic if ignored. Typical failure mileage: 60k-120k.
The BMW 420d is powered by either the N47D20C (2013-2015) or the B47D20A (2015-present). While the B47 is significantly more reliable, N47-equipped 420ds have a well-documented timing chain weakness that drives most replacement decisions. Rebuilt engines through EnginesMarket include upgraded components addressing the original failure point, plus a minimum 12-month unlimited-mileage warranty.
Why the BMW 4 Series 420d N47 Engine Wears Prematurely
Affected Vehicles
BMW 4 Series 420d (N47D20C, 2013-2015)
Typical Failure Mileage
60k-120k
Root Cause
The N47's rear-mounted timing chain design uses components that stretch over time, particularly where oil service intervals have been extended. A rattling noise from the rear of the engine on cold start is the primary warning sign.
Why It Happens
The N47's rear-mounted timing chain design uses components that stretch over time, particularly where oil service intervals have been extended. A rattling noise from the rear of the engine on cold start is the primary warning sign.
Dealer (parts + labour)
£2,200+
Specialist (parts + labour)
£1,200-£1,800
What it involves
Chain kit replacement only, no engine removal required on some variants
Suitability
Best if caught early (cold-start rattle only, no misfires)
1 - 2 daysDealer (parts + labour)
£5,000-£8,000
Specialist (parts + labour)
£4,500-£6,500
What it involves
Supply & fit, upgraded components addressing the original failure point, 12-month warranty【EM-QUOTE】
Suitability
When chain has snapped or engine is otherwise damaged
1 - 2 daysAll prices are indicative UK market ranges based on current UK specialist supplier data.| Repair Tier | Dealer (Parts + Labour) | Specialist (Parts + Labour) | What It Involves | Suitability | Estimated Time |
|---|---|---|---|---|---|
 Timing chain replacement (preventative) Minor | £2,200+ | £1,200-£1,800 | Chain kit replacement only, no engine removal required on some variants | Best if caught early (cold-start rattle only, no misfires) | 1 - 2 days |
 Full Replacement - rebuilt/reconditioned engine Best Value | £5,000-£8,000 | £4,500-£6,500 | Supply & fit, upgraded components addressing the original failure point, 12-month warranty【EM-QUOTE】 | When chain has snapped or engine is otherwise damaged | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 2013-2015 BMW 420d is worth approximately £3,780-£12,600 depending on mileage and condition. For sub-£5,000 examples, a used engine replacement typically makes more sense than a full rebuilt unit. For cars worth £8,000+, a reconditioned or rebuilt engine usually justifies the premium via warranty and reliability.
Our Recommendation
Our Recommendation
If you hear the tell-tale cold-start rattle and act quickly, a timing chain replacement (preventative) is the most cost-effective option. If the chain has already snapped or engine damage is extensive, replacement with a rebuilt B47D20A unit (with its improved chain design) is the smarter long-term play.
Don't Let Engine Failure Write Off Your BMW 4 Series 420d
Whether you're dealing with N47 timing chain failure or B47 EGR cooler issues, early diagnosis is key. A rebuilt engine through EnginesMarket comes with upgraded components addressing the original failure point, a minimum 12-month warranty, and nationwide delivery or supply & fit options - often at a fraction of main dealer prices.
Compare rebuilt N47D20C BMW 4 Series 420d engine prices
12-Month Minimum
UK Specialists Vetted
Best Price GuidanceImportant Information
Important Information
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific BMW 4 Series 420d. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW 4 Series 420d Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW 4 Series 420d engine replacement cost in the UK-
A replacement engine for a BMW 420d typically costs between £1,800 and £6,500 depending on condition【EM-QUOTE】. Used N47D20C units start from around £1,800, while reconditioned units range from £2,800 to £5,500. Rebuilt engines with warranty sit at £3,800-£6,500. Specialist fitting adds approximately £650-£910 in labour【EM-QUOTE】.
- Used: £1,800-£3,200
- Reconditioned: £2,800-£5,500
- Rebuilt: £3,800-£6,500
Question 2Which BMW 4 Series 420d engines have timing chain problems-
The N47D20C engine (fitted to 420d models from 2013-2015) has a well-documented timing chain weakness. The rear-mounted chain can stretch over time, particularly with extended oil service intervals. The later B47D20A engine (2015 onwards) addressed this issue with a revised front-chain design and is significantly more reliable.
- N47D20C: timing chain stretch risk - listen for cold-start rattle
- B47D20A: EGR cooler issues - recall applied, timing chain issues rare
Question 3Is it worth replacing the engine in a BMW 4 Series 420d-
A 2013-2015 420d is typically worth £3,780-£12,600. If your car is worth under £5,000, a used engine replacement is usually the most cost-effective route. For cars worth over £8,000, a reconditioned or rebuilt engine with warranty is a sound investment - especially if you plan to keep the car for 2+ years.
-> Compare 420d engine pricesQuestion 4How long does a BMW 4 Series 420d engine replacement take-
Supply-only engines are typically dispatched within 1-2 working days. Full supply & fit through a specialist workshop usually takes 2-3 days, depending on workshop availability and the complexity of the specific 420d variant (xDrive models may take slightly longer).
-> Find a BMW 420d specialistQuestion 5What's the difference between the BMW 420d and 425d engine-
The 420d uses a 2.0-litre four-cylinder diesel (N47D20C or B47D20A) producing 184-190hp. The 425d uses the same 2.0-litre B47D20B engine but with a twin-turbo setup producing 224hp. While both are 2.0-litre diesels, the 425d's additional turbo and higher output mean different engine codes and compatibility.
-> Get the right engine for your 420dQuestion 6Can I replace my N47 engine with a B47 in my BMW 420d-
Yes - the B47D20A is a direct replacement for the N47D20C in the 420d, as both engines share the same mounting points and transmission compatibility. Upgrading to a B47 offers improved reliability (revised timing chain design) and Euro 6 emissions compliance. Always verify compatibility via VIN check before ordering.
-> Verify your 420d engine compatibilityWhy Choose UsCompare BMW 4 Series 420dEngine PricesToday
1,450+ BMW 4 Series engines supplied through our network【EM-VERIFIED】
12-Month Warranty on every rebuilt BMW 420d engine
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