How much does a BMW 4 Series M440i engine replacement cost in the UK?

A reconditioned B58 engine typically costs £5,000–£7,500 supply only, with LCI-era units slightly higher. Fitting adds £1,200–£1,700. Use our calculator for a figure specific to your M440i.

Is the BMW M440i (B58) engine reliable?

Yes - the B58 is widely considered one of the most reliable modern BMW engines. It's a significant improvement over the N54 and N55. The main watchpoints are coolant loss, PCV valve failure, and oil filter housing leaks - all manageable with proper maintenance.

What are the common problems with the BMW M440i engine?

Coolant loss (water pump, expansion cap), PCV valve failure, oil filter housing leaks, and occasional water pump failure. The engine itself is fundamentally robust and not prone to major failures.

Is it worth replacing an M440i engine, or should I scrap the car?

Depends on vehicle value. A G22 M440i is a £25,000–£45,000 vehicle - a £6,000 recon is 13–24% of the car's value, making replacement a clear decision. This is well within our 70% BMW scrap threshold.

How do I find my BMW M440i engine code?

Listed on the VIN plate and vehicle documentation. The M440i engine code is B58B30O1 (pre‑LCI, 2020–2024) or B58B30M2 (LCI, 2024+). Tell us your registration date and we'll confirm it for free.

Can I prevent the common failures on an M440i?

Yes - regular cooling system inspections, BMW‑spec oil changes with shortened intervals (5,000–7,500 miles), and PCV system checks are the most effective prevention. If you notice coolant loss or rough running, book an inspection immediately.

BMW 4 Series M440i2020–presentB58

BMW 4 Series M440i Engine Replacement — Compare Prices & Get Quotes

The M440i packs BMW's legendary B58 3.0‑litre straight‑six turbo with 48V mild‑hybrid assistance - the heart of the 4 Series range since 2020. Get quotes from trusted UK specialists today.

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4 Series M440i Engines - from £3,000 to £8,500B58

4 Series M440i Engines - from £3,000 to £8,500· B58

Instant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK-Wide Network

The M440i THROUGH TIME - Era Map

Four generations. Four eras. One guide to reliability, costs and what really matters.

GenerationYearsEngine CodeReliabilityRecon CostEra Note

Why use this era map?

This table is the single source every other section on this page matches - Sections 2, 4 and 6 reference it rather than restating conflicting figures.

Real UK Cost Data

Verified Reliability

Expert Insights

Updated for 2025

BMW 4 Series M440i Engine Replacement Costs

Supply Only£5,000–£7,500

Fitted (Indie)£6,300–£8,900

Warranty12–24 months

Best ForMost owners - best cost/warranty balance

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£3,000–£4,500£4,200–£5,9001–6 monthsBudget priority; lower-mileage donor

Reconditioned Engine£5,000–£7,500£6,300–£8,90012–24 monthsMost owners - best cost/warranty balance

Rebuilt Engine£6,000–£8,500£7,300–£9,90012–24 monthsLong-term ownership; 3+ year horizon

Main Dealer New£8,500–£12,000£9,800–£13,50024–36 monthsInsurance jobs, warranty claims

Figures above reflect the current B58 generation; LCI-era pricing runs slightly higher - see the Era Map above.

Labour estimate: Fitting a 4 Series M440i engine typically takes 12–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).

→ Compare M440i engine prices from UK specialists

Common Problems With BMW 320d Engines

1. Coolant Loss (Reservoir Cap / Water Pump)

Symptoms: Low coolant warning light, sudden drop in coolant level, overheating, visible coolant puddles under the car.

Typical mileage: 40,000–80,000 miles

Repair cost: £400–£900 (water pump or cap replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟠 Check - book inspection urgently if coolant levels drop

Our recommendation:

B58 coolant loss is one of the most frequently reported issues . The electric water pump can fail, and the expansion tank cap may not seal properly. If you notice the coolant level dropping, have the cooling system pressure‑tested immediately. Replacing a failing water pump preventatively is far cheaper than the overheating damage it can cause .

1. Coolant Loss (Reservoir Cap / Water Pump)

Symptoms: Low coolant warning light, sudden drop in coolant level, overheating, visible coolant puddles under the car.

Typical mileage: 40,000–80,000 miles

Repair cost: £400–£900 (water pump or cap replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟠 Check - book inspection urgently if coolant levels drop

Our recommendation:

2. PCV Valve Failure

Symptoms: Rough idle, engine misfires, oil in the intake/charge pipe, check engine light, whistling noise from the engine.

Typical mileage: 50,000–90,000 miles

Repair cost: £400–£800 (PCV valve replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟡 Monitor - book inspection soon

Our recommendation:

The PCV valve is a well‑known weak point on the B58 . If you notice a rough idle, misfires, or oil in the intake, have the PCV system inspected. A failed PCV valve can cause oil consumption and performance issues. Replacing it promptly prevents more serious engine damage.

3. Oil Filter Housing Leak

Symptoms: Oil or coolant leak from the front of the engine, low oil warning light, low coolant warning, burning oil smell.

Typical mileage: 60,000–100,000 miles

Repair cost: £800–£1,500 (oil filter housing replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟡 Monitor - book inspection soon

Our recommendation:

The plastic oil filter housing on the B58 can crack and leak oil or coolant . Some owners have reported failures as early as 60,000 miles . If you notice oil or coolant residue on the front of the engine, have the oil filter housing inspected. An upgraded aluminium housing is available as a permanent fix .

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M440i - Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

M440i - Repair, Buy, or Replace?

Every 320d has a story. Make the right call with clear data, real-world costs, and honest guidance from UK specialists.

Can It Be Repaired?

ProblemRepairable?Typical CostWhen It Makes SenseCoolant loss (water pump/cap)✅ Yes£400–£900Routine maintenance - do preventativelyPCV valve failure✅ Yes£400–£800Straightforward - replace valveOil filter housing leak✅ Yes£800–£1,500Replace with upgraded aluminium housingTurbocharger wastegate rattle⚠️ Sometimes£1,000–£2,500Viable on lower-mileage examples; assess overall turbo healthSevere engine damage (overheating / oil starvation)❌ Usually NoEngine replacementLittle left to salvage - replacement is the only option

Buying This M440i? Check These First

Buy If

Documented cooling system maintenance (water pump, expansion tank)
PCV valve replaced or inspected
Oil filter housing replaced with upgraded aluminium unit
Full BMW service history with correct oil spec

Avoid If

Coolant loss with no diagnosis - walk away
Rough idle with no PCV history - may indicate PCV failure
Oil/coolant residue on the engine - oil filter housing may be failing
Engine warning light with no diagnosis - potentially expensive

Closing Verdict

The B58 is one of BMW's finest modern engines - a 3.0‑litre straight‑six with 374–386 hp, 500–540 Nm and genuine performance credentials. It's not without its watchpoints - coolant system, PCV valve and oil filter housing are the main areas to monitor - but it's fundamentally robust and significantly more reliable than earlier BMW turbo sixes. Buy on full service history and pay attention to coolant levels. A well‑maintained M440i is a long‑lived performance car.

Don't guess.Get the right engine at the right price.

→ Compare M440i engine prices before you buy

Don't Guess. Compare.

Get real quotes from vetted UK specialists and make the right call for your 320d.

→ Compare M440i engine prices before you buy

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Buying Checklist

Before you buy a used BMW 4 Series M440i (or before you commit to an engine replacement), check these:

Coolant Level

Check for unexplained loss; water pump or cap may be failing

Cold Start

Listen for smooth start; B58 is generally quiet

Rough Idle

Check for uneven running; PCV valve failure indicator

Oil/Coolant Residue

Check front of engine; oil filter housing leak indicator

Service History

including which generation (pre‑LCI or LCI) and confirmed maintenance

Oil Consumption

Does it use more than 1L per 1,000 miles?

Engine Warning Light

Have codes been read? Any unresolved issues?

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 320d pitfalls.

Buy smart. Drive with confidence.

A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 320d pitfalls.

BMW 320d Engine Codes

This table's rows match Section 1B's Era Map exactly.

B58B30O1 (3.0 straight-six turbo, 48V MHEV)

Years2020–2024

Power374 PS (275 kW) @ 5,500–6,500 rpm; 500 Nm @ 1,800–5,000 rpm + 11 hp e‑boost

2025 Enquiries- (pattern data)

Avg. Recon Cost£5,000–£7,500 [PLACEHOLDER]

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

B58B30O1 (3.0 straight-six turbo, 48V MHEV)2020–2024374 PS (275 kW) @ 5,500–6,500 rpm; 500 Nm @ 1,800–5,000 rpm + 11 hp e‑boost- (pattern data)£5,000–£7,500 [PLACEHOLDER]

B58B30M2 (3.0 straight-six turbo, 48V MHEV)2024–present386 PS (285 kW) @ 5,200–6,250 rpm; 540 Nm @ 1,900–4,800 rpm- (pattern data)£5,500–£8,000 [PLACEHOLDER]

Technical Specs

B58B30O1 3.0 straight-six

Displacement2,998 cc

Cylinders6-cylinder inline

Compression Ratio11.0:1

Fuel SystemDirect injection

TurbochargerSingle-turbo (twin-scroll) + 48V MHEV starter-generator

→ Compare M440i engine prices for your BMW

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Market Intelligence

Most Common Failure

Coolant system issues (water pump, expansion cap)

the most frequently reported B58 problem

Average Enquiry Mileage

40,000

–60,000 miles

[PATTERN DATA]

Average Replacement Cost

£6,000

reconditioned, supply only

[PLACEHOLDER - confirm vs cost sheet]

Most Requested Engine Code

B58B30O1

[PATTERN DATA]

Peak Enquiry Season

Summer

cooling issues exposed by warmer weather

[PATTERN DATA]

Regional Demand

South East18%

London16%

North West12%

PATTERN DATA

Regional Demand Breakdown

18%South East

16%London

12%North West

BMW 320d - Frequently Asked Questions

All prices are indicative UK market ranges based on historical quote data from our network of engine specialists. Actual costs vary by variant, engine code, 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.

Find the best BMW 4 Series M440i engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and get back on the road with confidence - from £3,000 for a used unit to £8,500 for a fully rebuilt straight‑six.

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100% Free

No hidden fees

No Obligation

Get quotes with zero pressure

UK Specialists

20+ vetted experts

12-Month Warranty

As standard

Nationwide Delivery

Supply & fit available