BMW X3 M40i Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK BMW X3 M40i engine specialists. Compare prices on reconditioned, rebuilt and used B58 engines for your M40i - supply and fit available across the UK.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £4,000 to £7,000
Used from £3,500 · Reconditioned from £4,000 · Common codes: B58B30, B58B30O1
From £3,500
Tested, bare/short engine
From £4,000
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 X3 M40i specialists.
3 Simple Steps3 Simple Stepsto Finding the Best BMW X3 M40i Replacement Engineto Finding the Best BMW X3 M40i Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryBMW X3 M40i - Engine History & Specs at a Glance
The BMW X3 M40i joined the G01 generation as the performance flagship petrol model, powered by the legendary B58 straight-six engine. Over the G01 production run, the M40i badge carried the B58B30 engine with two distinct power outputs - the earlier 355hp and the later 382hp version with 48V mild hybrid assistance.
Variant HistoryBMW X3 M40i - Engine History & Specs at a Glance
The BMW X3 M40i joined the G01 generation as the performance flagship petrol model, powered by the legendary B58 straight-six engine. Over the G01 production run, the M40i badge carried the B58B30 engine with two distinct power outputs - the earlier 355hp and the later 382hp version with 48V mild hybrid assistance.
BMW X3 M40i
Fuel TypePetrol
Engine Size3.0L (2,998cc)
Power Output Range355-382hp across the variant's historyEngine History Timeline
G01 X3 M40i debuts with B58B30 3.0-litre straight-six petrol, 355hp, 500Nm torque, all-wheel drive
Minor ECU calibration update; no power change
B58B30 receives power increase to 382hp 500Nm torque
48V mild hybrid starter-generator introduced on some markets
G01 LCI facelift; M40i continues with B58B30O1 382hp, 48V MHEV
G01 production ends; G45 X3 M50 replaces M40i with 393hp B58B30M2
Key Specs Snapshot
Fuel TypePetrolEngine Size3.0L (2,998cc)Power Output Range355-382hp across the variant's historyYears Produced2018-2024Every engine fitted to the BMW X3 M40i is covered below, with UK rebuilt pricing and known failure points.
BMW X3 M40i Engine Codes - Specifications & Replacement CostBMW X3 M40i Engine Codes - Specifications & Replacement Cost
3.0 Petrol (2018-2020)
Power Output355hp, 500Nm torqueYears Fitted2018-2020
Compatible Trim Levels
- X3 M40i
- X3 M40i M Sport
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£3,500-£5,500
Reconditioned
Addressed known issues, tested
£4,000-£7,000
Rebuilt
Full teardown, upgraded internals
£4,000-£7,000
Common Failure
Coolant transfer pipe failure (plastic pipe at front of engine, common weak point); PCV diaphragm failure on higher-mileage units; oil filter housing gasket leaks.
The BMW X3 M40i is powered by the B58B30 straight-six turbo petrol - widely regarded as one of BMW's best modern engines. With a closed-deck block, forged internals, and twin-scroll turbo technology, the B58 delivers effortless power and exceptional refinement. However, coolant transfer pipe failure, PCV system issues, and oil leaks are the most common failure points. Every rebuilt engine supplied through EnginesMarket includes upgraded components addressing the original failure point, plus a minimum 12-month unlimited-mileage warranty.
Why the BMW X3 M40i B58 Suffers Sudden Coolant Loss
Affected Vehicles
BMW X3 M40i (B58B30, 2018-2024)
Typical Failure Mileage
30,000-70,000 miles
Root Cause
The factory plastic coolant transfer pipe at the front of the B58 engine becomes brittle under repeated thermal cycling, developing cracks that cause sudden and rapid coolant loss. The engine management system reduces power, but continued driving causes overheating and head gasket failure.
Why It Happens
The factory plastic coolant transfer pipe at the front of the B58 engine becomes brittle under repeated thermal cycling, developing cracks that cause sudden and rapid coolant loss. The engine management system reduces power, but continued driving causes overheating and head gasket failure.
Dealer (parts + labour)
£1,200-£1,800
Specialist (parts + labour)
£700-£1,100
What it involves
Replace plastic pipe with updated version, bleed cooling system
Suitability
Labour-intensive due to intake removal; permanent fix with revised pipe
1 - 2 daysDealer (parts + labour)
£3,500-£5,000
Specialist (parts + labour)
£2,200-£3,500
What it involves
Pipe replacement plus cylinder head gasket, head skim, pressure test
Suitability
Viable if head not warped
1 - 2 daysDealer (parts + labour)
£7,000-£10,000
Specialist (parts + labour)
£5,000-£7,500
What it involves
Supply & fit, rebuilt B58 unit with revised cooling components, full warranty
Suitability
Required after severe overheating event
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 |
|---|---|---|---|---|---|
 Coolant transfer pipe replacement Minor | £1,200-£1,800 | £700-£1,100 | Replace plastic pipe with updated version, bleed cooling system | Labour-intensive due to intake removal; permanent fix with revised pipe | 1 - 2 days |
 Pipe + head gasket Best Value | £3,500-£5,000 | £2,200-£3,500 | Pipe replacement plus cylinder head gasket, head skim, pressure test | Viable if head not warped | 1 - 2 days |
Full Replacement - rebuilt/reconditioned engine Best Value | £7,000-£10,000 | £5,000-£7,500 | Supply & fit, rebuilt B58 unit with revised cooling components, full warranty | Required after severe overheating event | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 2018-2024 BMW X3 M40i is worth approximately £25,000-£55,000. Replacement cost is typically small relative to vehicle value, making a rebuilt engine a viable option if needed. For a £30,000+ M40i, a £5,000-£7,500 rebuilt engine is a sensible investment.
Our Recommendation
Our Recommendation
B58 coolant leaks are the single most discussed issue on X3 M40i forums. If you smell coolant or see the low coolant warning, act immediately. The preventative pipe replacement costs £700-£1,100 at a specialist - a small price on a £25,000+ car. Ignore it, and a £5,000-£7,500 rebuilt engine becomes the only fix. Check your coolant level monthly.
Don't Let Engine Failure Write Off Your BMW X3 M40i
The B58-powered BMW X3 M40i is one of the most desirable performance SUVs on the market, but its cooling system, PCV system, and oil seals require vigilance. Early detection of coolant loss, rough idle, or oil leaks can save the engine. Every rebuilt engine supplied through EnginesMarket carries a minimum 12-month unlimited-mileage warranty, with upgraded components addressing the original failure points. Compare quotes from UK specialists today.
Compare rebuilt B58B30 BMW X3 M40i 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 X3 M40i. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW X3 M40i Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW X3 M40i engine replacement cost-
A BMW X3 M40i engine replacement typically costs £3,500-£7,500 depending on the condition type and engine code. Used B58 engines start from around £3,500, reconditioned units from £4,000, and rebuilt engines with a 12-month warranty from £4,000. Labour for fitting adds approximately £600-£1,200 for an independent specialist.
- Used: £3,500-£5,500
- Reconditioned: £4,000-£7,000
- Rebuilt: £4,000-£7,000
- Fitting labour: 10-14 hours at £65/hr
Question 2Is the BMW X3 M40i B58 engine reliable-
Yes, the B58B30 is widely regarded as one of BMW's best modern engines. With a closed-deck block and forged internals, it delivers exceptional performance and reliability. However, coolant transfer pipe failure is a known weak point, and PCV system issues can occur at higher mileages. Regular maintenance with BMW Longlife-14 approved oil is essential.
- B58B30: widely regarded as BMW's best modern straight-six
- Coolant transfer pipe failure is the main concern
- PCV system failure can occur at 60k-100k miles
- Regular servicing with correct spec oil is essential
Question 3What causes the BMW X3 M40i coolant leak-
The most common cause is the coolant transfer pipe at the front of the B58 engine. The factory plastic pipe becomes brittle under thermal cycling and develops cracks, causing sudden coolant loss. BMW issued a revised pipe to address the issue, but many early M40is are still running the original plastic unit.
- Plastic coolant transfer pipe cracks under thermal stress
- Causes sudden coolant loss and potential overheating
- Upgraded aluminium pipe is available as a permanent fix
- Replace preventatively at 40,000 miles for peace of mind
Question 4How long does a BMW X3 M40i engine replacement take-
A typical BMW X3 M40i engine replacement takes 3-5 working days for a full rebuild, including parts sourcing, fitting, and testing. Supply-only engines can often be dispatched within 1-3 working days, with fitting then scheduled at your chosen specialist.
- Full rebuild with fitting: 3-5 working days
- Supply only: 1-3 working days
- Fitting labour: 10-14 hours at specialist rates
- Confirm exact timeline with your chosen supplier at booking
Question 5What's the difference between the BMW X3 M40i and X3 M-
The M40i is powered by the B58B30 straight-six (355-382hp), while the X3 M is powered by the S58B30 twin-turbo straight-six (480-510hp). Both are 3.0-litre petrol engines, but the S58 features a closed-deck block, forged internals, and twin mono-scroll turbos for significantly more power.
- M40i: B58B30, 355-382hp, single twin-scroll turbo
- X3 M: S58B30, 480-510hp, twin mono-scroll turbos
- Both share the same 3.0-litre straight-six architecture
- X3 M engines are significantly more expensive to replace
Question 6What engine code is in my BMW X3 M40i-
Your BMW X3 M40i will have one of two engine codes depending on its production year: B58B30 (2018-2020, 355hp) or B58B30O1 (2020-2024, 382hp with 48V MHEV). Enter your registration above to confirm the exact code fitted to your vehicle.
- 2018-2020: B58B30 (355hp)
- 2020-2024: B58B30O1 (382hp)
Why Choose UsCompare BMW X3 M40iEngine PricesToday
150+ BMW X3 M40i engines supplied through our network
12-Month Warranty on every rebuilt BMW X3 M40i engine
Nationwide UK delivery
supply & fit available
Comparing quotes for your BMW X3 M40i engine replacement is free, no-obligation, and specific to your exact vehicle and engine code. Enter your registration above to connect with vetted UK specialists who stock the right B58 engine for your M40i - whether you need a used unit, a reconditioned replacement, or a fully rebuilt engine with warranty.
Enter your registration
and get matched with verified BMW X3 M40i specialists.