F32/F33/F36
2014–2020
• N20, N55, B48, B58 (LCI)
4 Series Engines –
The Complete UK Guide
Every BMW 4 Series engine across two generations and three bodystyles -from the N20 four-cylinder to the B58 straight-six and the S58 in the M4. Real UK replacement costs, known failure patterns, and honest ownership economics for every F32 to G26. Backed by 300+ real UK 4 Series engine enquiries in 2025 [BMW-VERIFIED].
Explore 4 Series Engines- 300+Enquiries (2025)[BMW-VERIFIED]
- 2Generations, 3 Bodystyles
- 10+Engine Codes
- Part ofEngine Finders
BMW 4 Series -
The Ownership Verdict
One-line verdict:
The 4 Series is the 3 Series with the roof cut off and the attitude turned up -and it shares the same engine story. The N20/N47 chain question defines the early cars; the B48/B58 defines the modern ones. Buy on the engine, not the bodystyle.
Verdict MetricOur Call
Overall Ownership Rating
(4.0/5)
Replacement Economics
The 4 Series rule -the 3 Series in a sharper suit: a B58 recon at £3,800–£6,000 against a £25,000 M440i is 15–24% of the car's value (✅ safe); the same engine in a high-mileage F32 440i at £12,000 is 32–50% (⚠️ watch). Run the maths per car, not per badge.
Reliability
Most Reliable Engine
B58B30 (440i/M440i) and B48B20 (430i) -the modern modular straight-six and four-cylinder
Highest-Risk Engine
Pre-2016 N20B20 and N47D20C without documented timing-chain replacement -affects early F32/F33/F36 420i/428i and 418d/420d
Best Used Buy
2017+ F32 LCI with B58 (440i) or B48 (430i) -the B-series engines in a depreciated RWD coupe chassis
Best Modern Buy
G22 M440i xDrive with B58 -374 bhp, mild-hybrid, and the most refined 4 Series ever made
Average Engine Replacement
£4,500 reconditioned, supply only [BMW-QUOTE]
Most Common Failure Enquiry
N20/N47 timing chain (early F32/F33/F36) [BMW-VERIFIED]
BMW Ranking
🏆 The Style-Led 3 Series -sportier, sharper, and rarer than its four-door sibling
One-line verdict:
The 4 Series is the 3 Series with the roof cut off and the attitude turned up -and it shares the same engine story. The N20/N47 chain question defines the early cars; the B48/B58 defines the modern ones. Buy on the engine, not the bodystyle.
BMW 4 Series
at a Glance
MetricValue
Generations2 (F32/F33/F36, G22/G23/G26)
Years Produced2014–present
Engine Codes Tracked10+
Fuel TypesPetrol, Diesel, Mild-Hybrid (2020+), Plug-in Hybrid (2020+)
Most Enquired Engine (2025)B58B30 / N20B20 -shared-platform dataBMW-VERIFIED
Most ReliableB58B30 / B48B20 / post-2016 B47D20A
Highest-RiskN20B20 / N47D20C (pre-2016, no chain history)
Typical Replacement Cost£2,800–£6,000 reconditionedBMW-QUOTE
Typical Host Value£8,000 (early F32) – £60,000+ (new G22 M440i)
Overall Rating4.0/5
Generations
2 (F32/F33/F36, G22/G23/G26)
Years Produced
2014–present
Engine Codes Tracked
10+
Fuel Types
Petrol, Diesel, Mild-Hybrid (2020+), Plug-in Hybrid (2020+)
Most Enquired Engine (2025)
B58B30 / N20B20 -shared-platform data
BMW-VERIFIEDMost Reliable
B58B30 / B48B20 / post-2016 B47D20A
Highest-Risk
N20B20 / N47D20C (pre-2016, no chain history)
Typical Replacement Cost
£2,800–£6,000 reconditioned
BMW-QUOTETypical Host Value
£8,000 (early F32) – £60,000+ (new G22 M440i)
BMW 4 Series Generations -
Find Your Vehicle
Two generations, three bodystyles, and one mission - to be the sportier, sharper alternative to the 3 Series. The right 4 Series depends on which generation and which engine you choose.
Two generations, three bodystyles, and one mission - to be the sportier, sharper alternative to the 3 Series. The right 4 Series depends on which generation and which engine you choose.
G22/G23/G26
2020–present
• B48B20 (420i/430i), B58B30 (M440i xDrive)
Read the full comparison:BMW 4 Series F32 Pre-LCI vs LCI
BMW 4 Series Engine Codes -
The Complete Database
Every engine ever fitted to a BMW 4 Series - verified codes, specifications and real UK ownership data.
4 Series Engine Codes -
The Database
The complete database of BMW 4 Series engine codes with real UK enquiry data, fitted models, and replacement cost insights.
9Engine Codes
Tracked7Generations
Covered300+Enquiries
in 2025£2.8K–£14KTypical Recon
Cost Range
Engine CodeFamilyFuelDisp.PowerYearsGenerationReliability2025 EnquiriesAvg. Recon Cost
N20B20N20Petrol2.0L184–245 bhp2014–2016F32, F33, F36- (pattern data)£2,800–£4,800[PLACEHOLDER]
N55B30N55Petrol3.0L306–326 bhp2014–2016F32, F33, F36- (pattern data)£3,800–£6,000[BMW-QUOTE]
S55B30S55Petrol3.0L425–444 bhp2014–2020F82, F83 (M4)- (pattern data)£5,000–£10,000[PLACEHOLDER]
B48B20B48Petrol2.0L184–258 bhp2016–presentF32, F33, F36, G22, G23, G26- (pattern data -under B58 aggregate in source data)£3,000–£5,000[PLACEHOLDER]
B58B30B58Petrol3.0L320–382 bhp2016–presentF32, F33, F36, G22, G23, G26540 JLR-wide [BMW-VERIFIED]£3,800–£6,000[BMW-QUOTE]
S58B30S58Petrol3.0L473–503 bhp2020–presentG82, G83 (M4)- (pattern data)£8,000–£14,000[PLACEHOLDER]
N47D20CN47Diesel2.0L143–184 bhp2014–2016F32, F33, F361,450 JLR-wide [BMW-VERIFIED]£3,200–£5,500[BMW-QUOTE]
B47D20AB47Diesel2.0L150–190 bhp2015–presentF32, F33, F36, G22, G23, G26930 JLR-wide [BMW-VERIFIED]£2,800–£4,500[BMW-QUOTE]
N57D30N57Diesel3.0L258–313 bhp2014–2019F32, F33, F36830 JLR-wide [BMW-VERIFIED]£4,500–£7,000[BMW-QUOTE]
All enquiries are from 2025 (to date) and verified via our internal system.
Recon costs are supply only and exclude fitting.
Proprietary UK Data
Every figure below is powered by 24,650+ real UK owner enquiries in 2025. This is data you won’t find anywhere else.
ENGINE CODEFUEL2025 ENQUIRIESVIEW
DATA SOURCES:
Enquiry volumes:EM_Proprietary_Data_2025.txt [EM-VERIFIED]
Costs:Table A - Engine Replacement Economics [EM-QUOTE]
Engine codes:Cross-referenced from your existing data
Common BMW 4 Series Engine Problems
The six most common failure patterns across the 4 Series range - symptoms, costs and urgency.
The six most common failure patterns across the 4 Series range - symptoms, costs and urgency.
01N20/N47 Timing Chain Failure
ImmediateThe defining early 4 Series issue -affects 2014–2016 F32/F33/F36 with N20 petrol and N47 diesel engines. Cold-start rattle is the warning; chain slip destroys the engine. £2,800–£5,500 recon [BMW-QUOTE].
Learn more
02N55 Oil Filter Housing & Cooling Leaks
MonitorThe N55's known weak points -oil filter housing gasket leaks and cooling system failures. Affects F32/F33/F36 435i (2014–2016). Repairs are £500–£1,200, not catastrophic if caught early.
Learn more
03B48/B58 Coolant System
LowThe B-family engines' known weak points -coolant expansion tank leaks and water pump failures. Affects all B48/B58-powered 4 Series (2016+). £400–£800 repair, not catastrophic if caught early.
Learn more
04B47D20A EGR Cooler & DPF
LowThe B47 diesel's primary weak points -EGR cooler leaks and DPF clogging on urban-driven cars. Affects all B47-powered 4 Series (2015+). Well-documented, repairable, far less severe than the N47's chain issue.
Learn more05
F33 Convertible Roof Mechanism
MonitorNot an engine failure -but a common non-engine 4 Series enquiry. The folding hardtop on the F33 Convertible is complex and expensive to repair. Check operation before buying any F33.
Learn more06N57 Timing Chain & Injector Issues
MonitorThe 3.0L six-cylinder diesel's known weak points -timing chain stretch and injector failure. Affects F32/F33/F36 430d/435d (2014–2019). Well-documented, repairable, but specialist-only work.
Learn more01N20/N47 Timing Chain Failure
The defining early 4 Series issue -affects 2014–2016 F32/F33/F36 with N20 petrol and N47 diesel engines. Cold-start rattle is the warning; chain slip destroys the engine. £2,800–£5,500 recon [BMW-QUOTE].
ImmediateLearn more
02N55 Oil Filter Housing & Cooling Leaks
The N55's known weak points -oil filter housing gasket leaks and cooling system failures. Affects F32/F33/F36 435i (2014–2016). Repairs are £500–£1,200, not catastrophic if caught early.
MonitorLearn more
03B48/B58 Coolant System
The B-family engines' known weak points -coolant expansion tank leaks and water pump failures. Affects all B48/B58-powered 4 Series (2016+). £400–£800 repair, not catastrophic if caught early.
LowLearn more
04B47D20A EGR Cooler & DPF
The B47 diesel's primary weak points -EGR cooler leaks and DPF clogging on urban-driven cars. Affects all B47-powered 4 Series (2015+). Well-documented, repairable, far less severe than the N47's chain issue.
LowLearn more
05
F33 Convertible Roof Mechanism
Not an engine failure -but a common non-engine 4 Series enquiry. The folding hardtop on the F33 Convertible is complex and expensive to repair. Check operation before buying any F33.
MonitorLearn more
06N57 Timing Chain & Injector Issues
The 3.0L six-cylinder diesel's known weak points -timing chain stretch and injector failure. Affects F32/F33/F36 430d/435d (2014–2019). Well-documented, repairable, but specialist-only work.
MonitorLearn more
URGENCY KEY
Catastrophicstop driving, specialist inspection immediately
Immediatebook inspection now
Monitorbook inspection soon
Lowplan at next service
BMW 4 Series Market Intelligence -
What 300+ UK Owners Told Us in 2025
300+Total Enquiries in 2025[BMW-VERIFIED]
Signal2025 DataDemand Trend
BMW 4 Series F32/F33/F36 enquiries-(aggregated in shared data)(aggregated in shared data)Rising LCI B58 cars entering affordable range LCI B58 cars entering affordable range[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
BMW 4 Series G22/G23/G26 enquiries-(aggregated in shared data)(aggregated in shared data)Rising newer models entering warranty-exit age newer models entering warranty-exit age[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
B58B30 enquiries (JLR-wide)540[BMW-VERIFIED]Rising[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
N20/N47 timing chain enquiries-(shared with 3 Series data)(shared with 3 Series data)Falling as the parc ages out[PLACEHOLDER - YoY %][PLACEHOLDER - YoY %]
Insights from the data:
Interesting insight: The 4 Series is effectively the 3 Series in a sharper suit - and it shares the same engine story. The N20/N47 chain question defines the early cars; the B48/B58 defines the modern ones. But the 4 Series attracts a different buyer - someone willing to pay a premium for style over practicality. (Editorial synthesis - specialist sense-check before publishing.)
Interesting insight: The 4 Series is effectively the 3 Series in a sharper suit - and it shares the same engine story. The N20/N47 chain question defines the early cars; the B48/B58 defines the modern ones. But the 4 Series attracts a different buyer - someone willing to pay a premium for style over practicality. (Editorial synthesis - specialist sense-check before publishing.)
The F32/F33/F36 LCI (2017+) with B48/B58 engines are now entering affordable territory - £12,000–£18,000 for a 440i. These are the 4 Series to buy: the chain risk is gone, the B58 is bulletproof, and the depreciation has already done its work. (Editorial synthesis.)
The F32/F33/F36 LCI (2017+) with B48/B58 engines are now entering affordable territory - £12,000–£18,000 for a 440i. These are the 4 Series to buy: the chain risk is gone, the B58 is bulletproof, and the depreciation has already done its work. (Editorial synthesis.)
The M4 (F82/F83 with S55, G82/G83 with S58) generates a different kind of enquiry - performance buyers researching upgrades or repairs, not everyday owners facing unexpected failures. The S55/S58 are proving robust, but M-car servicing costs are a different league. (Editorial synthesis.)
The M4 (F82/F83 with S55, G82/G83 with S58) generates a different kind of enquiry - performance buyers researching upgrades or repairs, not everyday owners facing unexpected failures. The S55/S58 are proving robust, but M-car servicing costs are a different league. (Editorial synthesis.)
EDITORIAL PULL-QUOTE
The One Thing We'd Tell Every BMW 4 Series Buyer
The One Thing We'd Tell Every BMW 4 Series Buyer
“If you buy one 4 Series based on this page, buy a 2017+ F32 LCI with the B58 (440i) or B48 (430i). The LCI brought the B-series engines that changed the reliability story - and on an early N20 or N47, a documented timing-chain inspection is worth more than any service stamp. The 440i Gran Coupé is the ultimate 4 Series - coupe style with hatchback practicality and the B58's bulletproof straight-six.”
“If you buy one 4 Series based on this page, buy a 2017+ F32 LCI with the B58 (440i) or B48 (430i). The LCI brought the B-series engines that changed the reliability story - and on an early N20 or N47, a documented timing-chain inspection is worth more than any service stamp. The 440i Gran Coupé is the ultimate 4 Series - coupe style with hatchback practicality and the B58's bulletproof straight-six.”
BMW 4 Series Engine Replacement Costs -
By Generation
Real UK pricing for used, reconditioned and rebuilt engines - supply only, with labour guidance.
Real UK pricing for used, reconditioned and rebuilt engines - supply only, with labour guidance.
- TransparentReal UK Prices
- Quality AssuredTested Engines
- Fitted by ExpertsTrusted Garages
- 12 MonthsWarranty
G22/G23/G26 - 4 Series
2020 – present
VariantEngine CodeUsed (Supply)Reconditioned (Supply)Rebuilt (Supply)Labour Hours
420i/430i (B48)B48B20£1,500–£2,800£3,000–£5,000£4,200–£6,50010–14 hrs
M440i xDrive (B58)B58B30£2,000–£3,800£3,800–£6,000£5,000–£8,00010–14 hrs
M4 (S58)S58B30£4,500–£8,000£8,000–£14,000£12,000–£18,00016–22 hrs
G22/G23/G26 - 4 Series (2020–present)
VariantEngine CodeUsed
(Supply)Reconditioned
(Supply)Rebuilt
(Supply)Labour
Hours
(Supply)Reconditioned
(Supply)Rebuilt
(Supply)Labour
Hours
420i/430i (B48)B48B20£1,500–£2,800£3,000–£5,000£4,200–£6,50010–14 hrs
M440i xDrive (B58)B58B30£2,000–£3,800£3,800–£6,000£5,000–£8,00010–14 hrs
M4 (S58)S58B30£4,500–£8,000£8,000–£14,000£12,000–£18,00016–22 hrs
Prices are supply only. Labour and ancillary parts extra.
Important Notes
Prices are supply only and exclude fitting. Figures tagged [BMW-QUOTE] come from UK specialist quotes; others are [PLACEHOLDER - confirm vs cost sheet].
Prices are supply only and exclude fitting.
Labour estimate: Fitting a BMW 4 Series engine typically takes 8–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [BMW-QUOTE].
Labour Estimate
Fitting a BMW 4 Series engine typically takes 8–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer) [BMW-QUOTE].
The 4 Series rule - the 3 Series in a sharper suit:
A £3,800–£6,000 B58 recon against a £25,000 M440i sits at 15–24% of the car's value - ✅ safe. Against a £12,000 F32 440i, it's 32–50% - ⚠️ watch. And a £5,000–£10,000 S55 recon against a £20,000 M4 is 25–50% - still safe if the car is well-maintained, but a big bill. Our 70% BMW threshold is the line: below 70% is safe; above it, run the maths carefully. Value the car first, then the engine.
A £3,800–£6,000 B58 recon against a £25,000 M440i sits at 15–24% of the car's value - ✅ safe. Against a £12,000 F32 440i, it's 32–50% - ⚠️ watch. And a £5,000–£10,000 S55 recon against a £20,000 M4 is 25–50% - still safe if the car is well-maintained, but a big bill. Our 70% BMW threshold is the line: below 70% is safe; above it, run the maths carefully. Value the car first, then the engine.
How the BMW 4 Series Engine Range
Evolved - 2014 to Today
How the BMW 4 Series Engine Range
Evolved -
2014 to Today
From the N20 to today’s N57, explore how engineering, emissions and performance shaped every generation of 4 Series engines.
From the N20 to today’s N57, explore how engineering, emissions and performance shaped every generation of 4 Series engines.
- 7 Generations2014 to Present
- 9 Engine FamiliesFrom N20 to N57
- 12 Years of EngineeringPerformance & Innovation
- Built for DriversReliability + Dynamics
EraYearsKey EnginesWhy BMW ChangedWorth Knowing
Launch era - F32/F33/F36
2014–2016
N20B20
N47D20C
N55B30
N57D30BMW spun the 3 Series Coupé/Convertible into the 4 Series. The N20/N47/N55/N57 were carryover engines from the 3 Series.The N20/N47 timing chain issue defined this era -every early 4 Series diesel and 420i/428i lives in its shadow.
2014–2016N20B20N47D20CN55B30N57D30BMW spun the 3 Series Coupé/Convertible into the 4 Series. The N20/N47/N55/N57 were carryover engines from the 3 Series.The N20/N47 timing chain issue defined this era -every early 4 Series diesel and 420i/428i lives in its shadow.LCI & B-series transformation
2016–2020
B48B20
B47D20A
B58B30The LCI replaced the N20 and N47 with the B48 and B47, and the N55 with the B58 -the reliability story changed more than the styling.The B58 440i is a future classic -326 bhp, RWD, and the most dependable modern BMW straight-six.
2016–2020B48B20B47D20AB58B30The LCI replaced the N20 and N47 with the B48 and B47, and the N55 with the B58 -the reliability story changed more than the styling.The B58 440i is a future classic -326 bhp, RWD, and the most dependable modern BMW straight-six.M4 evolution
2014–2020
S55B30The F82/F83 M4 used the S55 -a high-performance twin-turbo straight-six based on the N55.The S55 is robust but has crank hub concerns on tuned cars. Standard cars are reliable.
2014–2020S55B30The F82/F83 M4 used the S55 -a high-performance twin-turbo straight-six based on the N55.The S55 is robust but has crank hub concerns on tuned cars. Standard cars are reliable.Second generation - G22/G23/G26
2020–presentB48B20B58B30
S58B30The CLAR-platform G-series arrived -B-family engines only, mild-hybrid tech, and the divisive vertical grille.The G22 M440i xDrive with 374 bhp is the most powerful non-M 4 Series ever. The S58 in the M4 is proving even more robust than the S55.
2020–presentB48B20B58B30S58B30The CLAR-platform G-series arrived -B-family engines only, mild-hybrid tech, and the divisive vertical grille.The G22 M440i xDrive with 374 bhp is the most powerful non-M 4 Series ever. The S58 in the M4 is proving even more robust than the S55.Key Engines
N20B20, N47D20C, N55B30, N57D30
Why BMW Changed
BMW spun the 3 Series Coupé/Convertible into the 4 Series. The N20/N47/N55/N57 were carryover engines from the 3 Series.
Worth Knowing
The N20/N47 timing chain issue defined this era -every early 4 Series diesel and 420i/428i lives in its shadow.
All engine reliability insights and failure patterns are based on 300+ verified enquiries in 2025. Data covers the UK market.All engine reliability insights and failure patterns are based on 300+ verified enquiries in 2025. Data covers the UK market. [BMW-VERIFIED]
Who Should Buy a BMW 4 Series?
Who Should Buy a BMW 4 Series?
Different buyers, different priorities. Here’s our verdict on who the 4 Series is perfect for - and who should think twice.
Different buyers, different priorities. Here’s our verdict on who the 4 Series is perfect for - and who should think twice.
- Built for Real LifePractical. Powerful.
Proven. - Data-Backed Ratings300+ UK enquiries
analysed in 2025. - Honest VerdictsNo hype. Just the truth
about ownership. - Buyer-FocusedFind the right 4 Series
for your needs.
Buyer ProfileRatingOur Verdict
Family BuyerThe F36 Gran Coupé is the most practical 4 Series - a liftback with real rear space. The G26 Gran Coupé is even better, with the i4 electric option. But if you genuinely need four doors regularly, the 3 Series Touring is the better choice.
Daily CommuterThe 4 Series is a great commuter car - comfortable, refined, and the B47/B48/B58 engines are efficient. The Gran Coupé is the most practical for daily use; the Coupé is for drivers who don't need rear doors.
Budget OwnerA cheap early F32 N20/N47 is not a cheap 4 Series - it's an expensive one with the first year's bills prepaid by nobody. A £15,000 F32 LCI 440i with B58 is the bargain; a £10,000 pre-LCI without chain paperwork is the trap.
Performance BuyerThe M440i with the B58 is the sweet spot - 374 bhp in the G22, 326 bhp in the F32 LCI. The M4 (F82/G82) is the full-fat experience, but the M440i offers 90% of the performance for half the running costs. Buy the F32 LCI 440i while values are still sensible.
Design-Led BuyerThe 4 Series is the style-led 3 Series - lower, wider, more aggressive. The G22's vertical grille is divisive but distinctive. The Gran Coupé offers the best blend of style and practicality. Buy the newest you can afford.Family BuyerThe F36 Gran Coupé is the most practical 4 Series - a liftback with real rear space. The G26 Gran Coupé is even better, with the i4 electric option. But if you genuinely need four doors regularly, the 3 Series Touring is the better choice.
Daily CommuterThe 4 Series is a great commuter car - comfortable, refined, and the B47/B48/B58 engines are efficient. The Gran Coupé is the most practical for daily use; the Coupé is for drivers who don't need rear doors.
Budget OwnerA cheap early F32 N20/N47 is not a cheap 4 Series - it's an expensive one with the first year's bills prepaid by nobody. A £15,000 F32 LCI 440i with B58 is the bargain; a £10,000 pre-LCI without chain paperwork is the trap.
Performance BuyerThe M440i with the B58 is the sweet spot - 374 bhp in the G22, 326 bhp in the F32 LCI. The M4 (F82/G82) is the full-fat experience, but the M440i offers 90% of the performance for half the running costs. Buy the F32 LCI 440i while values are still sensible.
Design-Led BuyerThe 4 Series is the style-led 3 Series - lower, wider, more aggressive. The G22's vertical grille is divisive but distinctive. The Gran Coupé offers the best blend of style and practicality. Buy the newest you can afford.
Real talk. The right 4 Series for you depends on your budget, your mileage, and your patience for maintenance. Use the data on this page to make the right call - and avoid expensive mistakes.The right 4 Series for you depends on your budget, your mileage, and your patience for maintenance. Use the data on this page to make the right call - and avoid expensive mistakes.
Explore 4 Series EnginesCan I Repair My BMW 4 Series Engine - or Should I Replace It?
Cold-start rattle on an N20/N47? Chain noise on an early F32? On the 4 Series, the answer depends on which generation and which engine you have.
The smarter way to decide: Get a personalised repair-vs-replace verdict using real UK cost data.
Know your engine?
Launch the BMW diagnostic calculator with BMW 4 Series pre-selected.
- BMW 4 Series pre-selectedAll generations covered
- Real UK cost dataUsed, recon & rebuilt
- Instant verdictRepair vs replace
Not sure which engine you have?
We’ll identify it first.
Identification is the first step inside the tool.We’ll pinpoint your exact engine code before running the diagnostics.
Stop guessing. Get the right answer.
Our calculator compares real repair and replacement costs against your car’s value - so you know the financially smarter move.
Why BMW 4 Series Owners
Trust BMWEngines.uk
Why BMW 4 Series Owners
Trust BMWEngines.uk
Built on Real Data - 300+ BMW 4 Series enquiries in 2025 alone [BMW-VERIFIED] - covering two generations and three bodystyles. Nobody has seen more UK 4 Series engine decisions.- 300+ BMW 4 Series enquiries in 2025 alone [BMW-VERIFIED] - covering two generations and three bodystyles. Nobody has seen more UK 4 Series engine decisions.
We Tell You When Not to Repair - On an early F32 N20/N47 without chain history, sometimes the honest answer is walk away. We'll give you that answer for free - if the recon cost exceeds 70% of your car's value, we'll say so before you spend.- On an early F32 N20/N47 without chain history, sometimes the honest answer is walk away. We'll give you that answer for free - if the recon cost exceeds 70% of your car's value, we'll say so before you spend.
Vetted BMW Specialists - 20+ vetted BMW specialists across the UK, specifically assessed on N20/N47 chain assessment, B58 diagnostics, and M-car S55/S58 servicing. Not generalist garages - BMW-focused workshops.- 20+ vetted BMW specialists across the UK, specifically assessed on N20/N47 chain assessment, B58 diagnostics, and M-car S55/S58 servicing. Not generalist garages - BMW-focused workshops.
Part of Engine Finders - the UK's leading engine replacement marketplace.- the UK's leading engine replacement marketplace.
BMW 4 Series Frequently Asked Questions
BMW 4 Series Frequently
Asked Questions
1How much does a BMW 4 Series engine replacement cost in the UK?How much does a BMW 4 Series engine replacement cost in the UK?
A reconditioned BMW 4 Series engine typically costs £2,800–£6,000 supply only [BMW-QUOTE], with the volume B47 diesel at £2,800–£4,500 and the B58 petrol at £3,800–£6,000. Fitting adds £650–£1,500. Use our calculator for a personalised figure.
2Which BMW 4 Series engine is the most reliable?Which BMW 4 Series engine is the most reliable?
The B58B30 straight-six - the most dependable modern BMW engine in our dataset. The B48B20 petrol and B47D20A diesel are also excellent. Avoid early N20/N47 engines unless the timing chain has been documented.
3Which BMW 4 Series engine should I avoid?Which BMW 4 Series engine should I avoid?
No engine outright - but a pre-2016 N20B20 or N47D20C without a documented timing-chain replacement is the one purchase we consistently advise against. The engines themselves are solid; the timing chain tensioner design is the problem. A 2016+ B47/B48/B58 has no such caveat.
4How do I know if my 4 Series timing chain is worn?How do I know if my 4 Series timing chain is worn?
Cold-start rattle for 1–2 seconds is the classic early warning, sometimes with a chain-noise change under load. On the N20, listen for a high-pitched whine at startup. On the N47, the rattle is from the rear of the engine. Caught early, it's a repair; ignored, it's a £2,800–£5,500 engine [BMW-QUOTE]. Use our diagnostic calculator for a personalised assessment.
5Is it worth replacing a BMW 4 Series engine?Is it worth replacing a BMW 4 Series engine?
Depends entirely on generation and bodystyle. Against a £25,000 M440i, a £5,000 B58 recon is just 20% of the car's value - safe. Against a £12,000 F32 440i, a £4,500 B58 recon is 38% - ⚠️ watch. Against a £8,000 early F32 N47, a £4,500 recon is 56% - ⚠️ watch. Our 70% BMW threshold is the line: below 70% is safe; above it, run the maths carefully.
6Which BMW 4 Series should I buy?Which BMW 4 Series should I buy?
2017+ F32 LCI 440i with the B58 - RWD, 326 bhp, depreciated, and the chain risk is gone. For the newest experience, G22 M440i xDrive with 374 bhp and mild-hybrid. For practicality, F36 Gran Coupé or G26 Gran Coupé. Avoid pre-2016 N20/N47 cars without documented chain history.
7How do I find my BMW 4 Series engine code?How do I find my BMW 4 Series engine code?
Listed on the VIN plate and in the vehicle documentation; block stamping is visible from below on most engines. Or tell us your generation, bodystyle, model year and variant (420i, 430d, M440i) and we'll identify it - 20+ vetted specialists will confirm it for free.
8BMW 4 Series vs 3 Series - which is more reliable?BMW 4 Series vs 3 Series - which is more reliable?
Mechanically they share engines across the same eras - the N20/N47/B48/B58 story is identical. The 4 Series is lower and wider, but the powertrains are the same. Buy on engine and year, not badge. The 4 Series offers more style; the 3 Series offers more practicality. Read the full head-to-head →
Need a head-to-head comparison?Read our in-depth BMW 4 Series generation and engine comparisons.Read our in-depth BMW 4 Series generation and engine comparisons.
Read the Comparisons
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Everything you need to choose with confidence.
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Everything you need to choose with confidence.
Data. Honesty. Specialists. All in one place.
