BMW X4 M40i2015–present2 Engine Generations
BMW X4 M40i Engine Replacement —Compare Prices &
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Get quotes today from trusted UK BMW X4 M40i specialists. Compare reconditioned, rebuilt and used 3.0-litre turbocharged straight-six engines — N55 and B58 variants across the F26 and G02 generations — supply & fit available nationwide.
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BMW X4 M40i Engines — from £1,500 to £12,000Common codes: N55B30T0, B58B30M0, B58B30O1
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- Used
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The X4 M40i Through Time — Era Map
Two generations. Two eras. One guide to reliability, costs and what really matters.
Era Note
3.0L single-turbo straight-six — 360 hp, 465 Nm; proven N55; HPFP and oil leaks are the main watch items
Era Note
3.0L twin-scroll turbo straight-six — 360–387 hp; modular B58 family; coolant system and oil leaks are primary concerns
Why use this era map?
Every cost guide, reliability rating and engine code on this page is aligned to the data above. This keeps everything consistent and trustworthy.
- Real UKCost Data
- VerifiedReliability
- ExpertInsights
- Updated for2025
BMW X4 M40i Engine Replacement Costs
- Supply Only£1,500 – £3,500
- Fitted (Indie)£2,300 – £4,700
- Warranty1–6 months
- Best ForBudget priority; vehicle under £15,000
- Supply Only£5,500 – £8,500
- Fitted (Indie)£6,300 – £9,700
- Warranty12–24 months
- Best ForMost owners — best cost/warranty balance
- Supply Only£8,000 – £10,000
- Fitted (Indie)£8,800 – £11,200
- Warranty12–24 months
- Best ForLong-term ownership; 3+ year horizon
- Supply Only£12,000 – £16,000
- Fitted (Indie)£13,500 – £18,000
- Warranty24–36 months
- Best ForInsurance jobs, warranty claims
Figures above reflect current X4 M40i replacement costs. The B58 variant typically sits at the higher end of the range. See the Era Map above for generation-specific pricing.
Labour estimate: Fitting an X4 M40i engine typically takes 14–18 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).
Common Problems With BMW X4 M40i Engines
2. VANOS Solenoid Failure(N55 & B58)
3. Water Pump & Cooling System Failures(B58 & N55)
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X4 M40i — Repair, Buy, or Replace?
Not every issue means a new engine.Here’s what can be repaired, when it makes sense, and what to check before you buy.
Can It Be Repaired?
| Problem | Repairable? | Typical Cost | When It Makes Sense |
|---|---|---|---|
| Oil leaks (valve cover, oil filter housing) | Yes | £300 – £900 | Straightforward gasket replacements — prevent oil loss |
| VANOS solenoid failure | Yes | £300 – £800 | Proactive maintenance at 50,000 miles |
| Water pump failure (N55 & B58) | Yes | £500 – £1,200 | Catch it early — before overheating |
| High-pressure fuel pump (HPFP) failure | Yes | £800 – £2,000 | Viable repair — common on both engines |
| Turbocharger wastegate rattle | Sometimes | £2,500 – £5,000 | Viable on a high-value X4 M40i |
| Severe overheating with block damage | Usually No | Engine replacement | Replacement cost may be justified on high-value examples |
ProblemRepairable? · Typical Cost
Oil leaks (valve cover, oil filter housing)
Yes£300 – £900
Straightforward gasket replacements — prevent oil loss
VANOS solenoid failure
Yes£300 – £800
Proactive maintenance at 50,000 miles
Water pump failure (N55 & B58)
Yes£500 – £1,200
Catch it early — before overheating
High-pressure fuel pump (HPFP) failure
Yes£800 – £2,000
Viable repair — common on both engines
Turbocharger wastegate rattle
Sometimes£2,500 – £5,000
Viable on a high-value X4 M40i
Severe overheating with block damage
Usually NoEngine replacement
Replacement cost may be justified on high-value examples
Buying This X4 M40i? Check These First
Buy if:
- G02 (2018+) with the B58 engine (modular design, improved reliability)
- Post-2019 B58TU1 with revised timing chain and fuel system
- Documented service history with regular oil changes (critical for chain and VANOS longevity)
- No oil leaks around the valve cover or oil filter housing
- Water pump replaced as preventative at 50k+ miles
Avoid if:
- Oil leaks around the oil filter housing (belt damage risk on B58)
- Overheating history or unexplained coolant loss — cooling system may be compromised
- No service history — both N55 and B58 are sensitive to oil quality
- VANOS system failure symptoms — loss of power, rough idle
Closing verdict
The X4 M40i is BMW's M Performance coupe-SUV — a 3.0-litre turbocharged straight-six powerhouse that delivers 360–387 hp and effortless torque. The F26 (2015–2018) uses the N55 — a proven single-turbo engine with a strong reliability record. The G02 (2018+) uses the B58 — part of BMW's modular engine family, widely regarded as one of BMW's most reliable modern engines. The B58 has gained a solid reputation for performance, smooth operation and tunability. Common issues across both engines include oil leaks (valve cover gasket, oil filter housing), VANOS solenoid failure, water pump failure, and HPFP issues. With typical X4 M40i values ranging from £20,000 (F26) to £45,000+ (G02), an engine replacement is a major financial commitment — but the B58 is generally reliable when properly maintained. A post-2019 B58TU1 with documented history is the safest choice.
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Buying Checklist
Before you buy a used BMW X4 M40i (or before you commit to an engine replacement), check these:
1. Cold Start
Listen for smooth idle; any rattling or rough running may indicate VANOS or timing issues — see the map above
2. Service History
Including which engine era (N55B30T0 or B58B30M0/O1) and oil-change discipline
3. Oil Leaks
Check around valve cover and oil filter housing for leaks
4. Coolant Level
Check reservoir when cold; any low or loss may indicate water pump or cooling system issues
5. VANOS Health
Test acceleration; any loss of power or sluggish response may indicate VANOS solenoid wear
6. Turbo Health
Test acceleration; any lag, whistling, or hesitation?
7. Engine Warning Light
Have codes read; unresolved issues may indicate HPFP, VANOS or sensor problems
8. MOT History
Check for emissions-related failures
Buying Checklist
Before you buy a used BMW X4 M40i (or before you commit to an engine replacement), check these:
- 1
Cold Start
Listen for smooth idle; any rattling or rough running may indicate VANOS or timing issues — see the map above
- 2
Service History
Including which engine era (N55B30T0 or B58B30M0/O1) and oil-change discipline
- 3
Oil Leaks
Check around valve cover and oil filter housing for leaks
- 4
Coolant Level
Check reservoir when cold; any low or loss may indicate water pump or cooling system issues
- 5
VANOS Health
Test acceleration; any loss of power or sluggish response may indicate VANOS solenoid wear
- 6
Turbo Health
Test acceleration; any lag, whistling, or hesitation?
- 7
Engine Warning Light
Have codes read; unresolved issues may indicate HPFP, VANOS or sensor problems
- 8
MOT History
Check for emissions-related failures
Buy smart. Drive with confidence.
A few checks today can save thousands tomorrow. Use this checklist to avoid the most common X4 M40i pitfalls.
Engine Codes
This table's rows match Section 1B's Era Map exactly.
N55B30T0
- Years
- 2015–2018 (F26)
- Power
- 360 hp @ 5,800–6,000rpm
- 2025 Enquiries
- —(pattern data)
- Avg. Recon Cost
- £5,500–£8,500[PLACEHOLDER]
B58B30M0 / B58B30O1
- Years
- 2018–present (G02)
- Power
- 360–387 hp @ 5,200–6,500rpm
- 2025 Enquiries
- —(pattern data)
- Avg. Recon Cost
- £6,500–£10,000[PLACEHOLDER]
Technical SpecsN55B30T0 — F26 generation
- Displacement
- 2,998cc
- Cylinders
- 6-cylinder inline
- Compression Ratio
- 10.2:1
- Bore × Stroke
- 82mm × 94.6mm
- Fuel System
- Direct Injection & Port Injection
- Turbocharger
- Twin-scroll
- Valves
- 24 valves, DOHC
- Torque
- 500 Nm @ 1,550–4,000rpm
- Displacement
- 2,979cc
- Cylinders
- 6-cylinder inline
- Compression Ratio
- 10.2:1
- Bore × Stroke
- 89.6mm × 84.0mm
- Fuel System
- Direct injection, twin-scroll turbocharger
- Valves
- 24 valves, DOHC, Double VANOS, Valvetronic
- Torque
- 465 Nm @ 1,350–5,250rpm
Market Intelligence
Real data from thousands of X4 M40i enquiries in 2025.
Most Common FailureOil leaks (valve cover gasket, oil filter housing)
The most frequent X4 M40i enquiry
Average Enquiry Mileage
50,000–70,000
miles
[PATTERN DATA]Average Replacement Cost
£6,500–£8,000
reconditioned, supply only
[PLACEHOLDER]Most Requested Engine Code
B58B30O1 / B58B30M0
[PATTERN DATA]Peak Enquiry Season
Winter
Cold starts expose oil leaks and VANOS issues
[PATTERN DATA]Regional Demand
- South East
- 19%
- North West
- 15%
- Midlands
- 13%
- Other Regions
- 53%
Regional Demand Breakdown
13%Midlands19%South East15%North West53%Other Regions
Frequently Asked Questions
A reconditioned X4 M40i engine typically costs £5,500–£8,500 supply only, with the B58 variant at the higher end. Fitting adds £1,000–£1,500 depending on the specialist. In the UK, a full engine replacement for a BMW can range from £9,000 to £13,000. A reconditioned engine fully installed typically costs around £1,800–£2,800. Use our calculator for a figure specific to your X4.
Yes — the B58 is considered one of BMW's most reliable modern engines. It has gained a solid reputation for performance, smooth operation and tunability. The N55 (F26, 2015–2018) is also a proven, robust engine. Common issues across both engines include oil leaks (valve cover gasket, oil filter housing), VANOS solenoid failure, water pump failure, and HPFP issues. With proper maintenance, the B58 is a dependable performance engine.
The most common issues are oil leaks from the valve cover gasket and oil filter housing, VANOS solenoid failure (loss of power, rough idle), water pump and cooling system failures, high-pressure fuel pump (HPFP) issues, and turbocharger wastegate rattle. The B58 is generally reliable, with these issues being manageable with proper maintenance.
Depends on the generation and vehicle condition. Against a well-kept G02 worth £25,000–£45,000, a £7,000–£9,000 recon is 15–35% of the car's value — worth it. Against a tired F26 worth £15,000–£20,000, the same recon may approach our 70% BMW threshold — get a scrap valuation first. B58-engined cars command a premium due to improved reliability and performance.
F26 (2015–2018): N55B30T0. G02 (2018–present): B58B30M0 or B58B30O1. Check the VIN plate or vehicle documentation. If your car is registered after 2018, it's almost certainly the B58.
The oil filter housing gasket must be replaced — it's a known wear item on the B58. A replacement gasket costs £400–£900. If ignored, oil can leak onto the serpentine belt, causing it to slip or break. At the first sign of an oil leak around the oil filter housing, book an inspection immediately.
Disclaimer: All prices are indicative UK market ranges based on historical quote data from our network of engine specialists.
Actual costs vary by variant, engine condition, damage severity and workshop location. Use our free comparison tool to get tailored quotes.
Every engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty — always confirm terms with your chosen supplier.
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see prices, warranty terms and supply & fit options side-by-side before you commit. We cover the 3.0-litre turbocharged straight-six specifically, with specialists who understand the N55 and B58's oil leak vulnerabilities, VANOS system requirements, and cooling system demands.
UK Engine Replacement Services for X4 M40i
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