BMW X4 F26Coupé SUV2014–2018
Every engine fitted to the first-generation X4 F26 – from the 2.0-litre N20 four-cylinder petrol and B47 diesel to the 3.0-litre N55 straight-six and the M40i's 360 hp B58.
Real UK replacement costs, honest reliability data, and the N20 timing chain guide weakness that defines this generation's ownership story.
Backed by real UK F26 enquiries in 2025 [BMW-VERIFIED].
Engine Database
Every engine fitted to the X4 F26 – from the entry-level four-cylinder to the range-topping M40i.
Overview
The BMW X4 F26, produced from July 2014 to March 2018, is the first-generation X4 and BMW's second "Sports Activity Coupé" (SAC) after the X6. Built on the BMW L7 platform shared with the F25 X3, the X4 is 23 mm longer and 37 mm taller than the X3 it is based on.
It features a sloping coupé-style roofline that trades some practicality for sportier styling, with all models featuring xDrive all-wheel drive and an 8-speed automatic transmission.
Key Facts
Market Intelligence
The F26 generated real UK engine enquiries in 2025 [BMW-VERIFIED], with the N20 petrol and N47/B47 diesel accounting for the majority of demand as these cars enter their second and third ownership cycles.
04Best & Worst Engines
Best Diesel Overall
B47D20A (xDrive20d, 2015–2018) – "The B47 is a significant improvement over the N47 – timing chain issues are less prevalent, the EGR cooler recall has been addressed, and it's smoother and cleaner. It's the diesel to choose for peace of mind."
“”
Who it's for: buyers who want diesel economy without the N47's timing chain anxiety.
Best Petrol Overall
B58B30M1 (X4 M40i, 2016–2018) – "The B58 straight-six delivers 360 hp of silky-smooth power with proven reliability and a sonorous exhaust note. It's a significant step up from the N55 – water pump and cooling system are the only real demands. This engine transforms the X4."
“”
Who it's for: buyers who want effortless performance and the best engine the F26 ever received.
Highest Risk
N20B20A (xDrive20i/28i, pre-2015) – "The N20 four-cylinder carries a significant timing chain guide weakness – failure can occur as early as 60,000 miles, leading to a £4,000+ engine replacement. Cold-start rattle is the warning sign. The N20 is the F26's biggest risk."
“”
Who it's for: only buyers who have confirmed chain guide replacement or are budgeting for it.
Most Expensive Failure
N57D30B (xDrive35d) – "The twin-turbo diesel produces 313 hp and 630 Nm of torque – impressive, but the complex turbo system and EGR cooler issues can lead to bills exceeding £5,000. This is not an engine for the faint-hearted."
“”
Who it's for: buyers who want diesel performance and accept the associated running costs.
Best Value
B58B30M1 (X4 M40i, 2016–2018) – "The M40i delivers 360 hp with none of the N20's timing chain anxiety. It's smoother, more reliable and more desirable than any other F26 engine – and values reflect that. The sweet spot of the range."
“”
Who it's for: buyers who want the best F26 money can buy.
Most Overlooked
N55B30A (xDrive35i, 2014–2018) – "The 306 hp straight-six is often overlooked in favour of the M40i, but it delivers effortless power with proven N55 reliability and lower running costs than the B58. It's the sensible performance choice for F26 buyers."
“”
Who it's for: buyers who want six-cylinder performance without the M40i premium.
Best Diesel Overall
B47D20A
(xDrive20d, 2015–2018) – "The B47 is a significant improvement over the N47 – timing chain issues are less prevalent, the EGR cooler recall has been addressed, and it's smoother and cleaner. It's the diesel to choose for peace of mind."
“”
Who it's for: buyers who want diesel economy without the N47's timing chain anxiety.
Best Petrol Overall
B58B30M1
(X4 M40i, 2016–2018) – "The B58 straight-six delivers 360 hp of silky-smooth power with proven reliability and a sonorous exhaust note. It's a significant step up from the N55 – water pump and cooling system are the only real demands. This engine transforms the X4."
“”
Who it's for: buyers who want effortless performance and the best engine the F26 ever received.
Highest Risk
N20B20A
(xDrive20i/28i, pre-2015) – "The N20 four-cylinder carries a significant timing chain guide weakness – failure can occur as early as 60,000 miles, leading to a £4,000+ engine replacement. Cold-start rattle is the warning sign. The N20 is the F26's biggest risk."
“”
Who it's for: only buyers who have confirmed chain guide replacement or are budgeting for it.
Most Expensive Failure
N57D30B
(xDrive35d) – "The twin-turbo diesel produces 313 hp and 630 Nm of torque – impressive, but the complex turbo system and EGR cooler issues can lead to bills exceeding £5,000. This is not an engine for the faint-hearted."
“”
Who it's for: buyers who want diesel performance and accept the associated running costs.
Best Value
B58B30M1
(X4 M40i, 2016–2018) – "The M40i delivers 360 hp with none of the N20's timing chain anxiety. It's smoother, more reliable and more desirable than any other F26 engine – and values reflect that. The sweet spot of the range."
“”
Who it's for: buyers who want the best F26 money can buy.
Most Overlooked
N55B30A (xDrive35i, 2014–2018) – "The 306 hp straight-six is often overlooked in favour of the M40i, but it delivers effortless power with proven N55 reliability and lower running costs than the B58. It's the sensible performance choice for F26 buyers."
“”
Who it's for: buyers who want six-cylinder performance without the M40i premium.
Engine
Typical Mileage
Common Major Failure
Repair Cost (Specialist)
Replacement Cost (Recon)
Ownership Verdict
High Risk – chain failure is a grenade; budget for replacement.
Solid – proven six, minor cooling issues.
Best Petrol – BMW's finest modern six.Watch – timing chain issues; avoid without history.Best Diesel – improved chain design; reliable.Solid – proven diesel six.Expensive – twin-turbo complexity.EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership VerdictHigh Risk – chain failure is a grenade; budget for replacement.Solid – proven six, minor cooling issues.Best Petrol – BMW's finest modern six.Watch – timing chain issues; avoid without history.Best Diesel – improved chain design; reliable.Solid – proven diesel six.Expensive – twin-turbo complexity.
The F26 rule
A £2,800–£5,000 B47/N47 recon against a £6,000–£15,000 F26 sits at 19–83% of the car's value. On a sub-£8,000 diesel F26, that brushes our 70% BMW threshold – we'll honestly tell you to walk away unless the car has documented chain work. Against a £12,000+ low-mileage example, the same recon drops to a routine 23–42% – a repair decision, not a financial one. For the M40i, a £7,000 B58 replacement is well within the value of a £20,000+ example.
Key Takeaways
Which F26 Costs Least To Own?
B47D20A (xDrive20d, post-2015) – proven diesel, reduced timing chain risk.
Which F26 Costs Most To Own?
N57D30B (xDrive35d) – twin-turbo complexity and premium running costs.
Which F26 Is Best Value?
B58B30M1 (X4 M40i) – the best engine in the range, with values to match.
N20
Timing Chain Guide Failure
Affected models:
F26 xDrive20i, xDrive28i (2014–2018, N20 engines).
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The plastic timing chain guides degrade and break, allowing the chain to slacken and skip teeth. Cold-start rattle for 1–2 seconds is the classic early warning. If ignored, the chain can snap, causing piston-to-valve contact and destroying the engine.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,500–£2,500
£800–£1,500
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£1,800–£4,500
Our Recommendation
If you own an N20-powered F26, treat the timing chain as an urgent inspection item – £800–£1,500 now is dramatically cheaper than the £1,800+ replacement that follows a failure. Any cold-start rattle should be investigated immediately.
N47
Timing Chain Stretch (2014–2015 Diesel)
Affected models:
F26 xDrive20d (N47D20A, 2014–2015).
Typical failure mileage:
60,000–120,000 miles.
Root cause:
The rear-mounted timing chain on the N47 diesel can stretch and wear the guides – a known issue from earlier BMW generations. Cold-start rattle is the warning sign, and failure leads to engine destruction.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£1,800–£2,800
£800–£1,500
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£2,800–£5,000
Our Recommendation
If you're considering a 2014–2015 diesel F26, budget for timing chain replacement if not already documented – £800–£1,500 now is cheap insurance against a £2,800+ replacement. Post-2015 B47 engines have improved chain design.
EGR
Cooler Failure (Diesel Engines)
Affected models:
F26 diesel variants (N47, B47, N57), particularly pre-2017 examples.
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The EGR cooler can develop internal coolant leaks, leading to coolant loss and potential engine damage. BMW has issued recalls for some variants.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500 (often covered by recall)
£400–£800
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£2,800–£5,000
Our Recommendation
Check if your F26 diesel is covered by the EGR cooler recall – if not, have the cooler inspected at every service. A £400–£800 repair is far cheaper than the £2,800+ replacement that follows an overheat.
N55/B58
Water Pump & Cooling System
Affected models:
F26 petrol variants with N55 or B58 engines (xDrive35i, X4 M40i).
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The plastic water pump impeller and thermostat housing can degrade with heat cycling – a known characteristic of BMW's six-cylinder engines. Coolant leaks are the first sign.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500
£400–£800
Catastrophic (Replacement)
Dealer
Specialist
£4,000–£7,000
£3,500–£6,000
Our Recommendation
At the first sign of coolant loss, have the water pump and thermostat housing inspected – a £400–£800 repair is cheap insurance against a £3,500+ replacement.
VariantEngine Code
Used (Supply)
Reconditioned (Supply)
Rebuilt (Supply)
Labour HoursScope note: All variants listed are F26 only. The G02 X4 (2018–present) is the successor generation with its own engine line-up – see the G02 Generation Page for those specifications. All F26 models feature xDrive all-wheel drive and an 8-speed automatic transmission as standard.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£8,000 supply only .
[BMW-QUOTE]
Most Common Failures
Live FeedBMW X4 xDrive20d
B47D20A
Birmingham
EGR cooler recall enquiry5
enquiries
Updated MonthlyBMW X4 M40i
B58B30M1
LondonCoolant loss3
enquiries
Updated MonthlyBMW X4 xDrive20i
N20B20A
ManchesterCold-start rattle3
enquiries
Updated MonthlyMost Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£8,000 supply only .
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£8,000 supply only .
[BMW-QUOTE]
Most Common Failures
Scope note: All variants listed are F26 only. The G02 X4 (2018–present) is the successor generation with its own engine line-up – see the G02 Generation Page for those specifications. All F26 models feature xDrive all-wheel drive and an 8-speed automatic transmission as standard.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£8,000 supply only .
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£8,000 supply only .
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£1,800–£8,000 supply only .
[BMW-QUOTE]
Most Common Failures
Live FeedBMW X4 xDrive20d
B47D20A
BirminghamEGR cooler recall enquiry5
enquiries
BMW X4 M40i
B58B30M1
LondonCoolant loss3
enquiries
BMW X4 xDrive20i
N20B20A
ManchesterCold-start rattle3
enquiries
Updated MonthlyTrusted F26 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real F26 owners, as part of the Engine Finders network.
Compare F26 Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit.
UK Engine Replacement Services for F26
covering every variant from xDrive20i to X4 M40i, with supply-only or full supply & fit available nationwide.
Find the best BMW X4 F26 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today and get back on the road with confidence.
Compare BMW X4 F26 Engine Prices on EnginesMarket
