How much does a BMW 3 Series M340d engine replacement cost in the UK?

A reconditioned B57D30T2 engine typically costs £5,000–£7,500 supply only, with LCI-era MHEV units slightly higher. Fitting adds £1,200–£1,700. Use our calculator for a figure specific to your M340d.

Is the BMW M340d engine reliable?

Yes - the B57 is a modern, well‑engineered straight‑six diesel. It's significantly more reliable than earlier BMW diesels like the N47. The main watchpoints are DPF clogging, EGR carbon build-up, wastegate actuator wear, and AdBlue system faults - all manageable with proper maintenance.

What are the common problems with the BMW M340d engine?

DPF clogging (short journey use), EGR valve and cooler carbon build-up, turbocharger wastegate actuator wear, AdBlue system faults, and coolant loss. The engine itself is fundamentally robust.

Is it worth replacing an M340d engine, or should I scrap the car?

Depends on vehicle value. A G20 M340d 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 M340d engine code?

Listed on the VIN plate and vehicle documentation. The M340d engine code is B57D30T2 - a 3.0-litre straight-six twin-turbo diesel. Tell us your registration date and we'll confirm it for free.

Can I prevent the common failures on an M340d?

Yes - regular long runs for DPF health, periodic EGR cleaning, and BMW-spec oil changes with shortened intervals (5,000–7,500 miles) are the most effective prevention. If you notice rattling or a drop in power, have the turbo system inspected immediately.

BMW 3 Series M340d2020–presentB57D30T2

BMW 3 Series M340d Engine Replacement — Compare Prices & Get Quotes

The M340d packs BMW's most potent straight-six diesel - the B57D30T2 with 340 bhp and 700 Nm of torque, paired with xDrive and 48V mild-hybrid technology. Get quotes from trusted UK specialists today.

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3 Series M340d Engines - from £3,000 to £8,500B57D30T2

3 Series M340d Engines - from £3,000 to £8,500· B57D30T2

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The M340d 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 3 Series M340d 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 B57D30T2 generation; LCI-era pricing runs slightly higher - see the Era Map above.

Labour estimate: Fitting a 3 Series M340d engine typically takes 12–16 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).

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Common Problems With BMW 320d Engines

1. DPF Clogging (Short Journey Use)

Symptoms: DPF warning light, reduced engine performance, increased fuel consumption, engine entering limp mode.

Typical mileage: 30,000–80,000 miles (depends on usage pattern)

Repair cost: £300–£800 (forced regeneration or DPF clean) / £1,500–£3,000 (DPF replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only (unless DPF is physically damaged)

🟡 Monitor - book inspection soon

Our recommendation:

Like all modern diesels, the B57 needs regular long runs for passive DPF regeneration. If your M340d is used primarily for short journeys, plan a 30–45 minute motorway run every two weeks. If the DPF warning light comes on, book a forced regeneration promptly - ignoring it can lead to costly DPF replacement.

1. DPF Clogging (Short Journey Use)

Symptoms: DPF warning light, reduced engine performance, increased fuel consumption, engine entering limp mode.

Typical mileage: 30,000–80,000 miles (depends on usage pattern)

Repair cost: £300–£800 (forced regeneration or DPF clean) / £1,500–£3,000 (DPF replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only (unless DPF is physically damaged)

🟡 Monitor - book inspection soon

Our recommendation:

2. EGR Valve and Cooler Carbon Build-up

Symptoms: Rough idling, reduced engine performance, increased fuel consumption, coolant loss (if cooler fails), engine warning light.

Typical mileage: 40,000–80,000 miles

Repair cost: £400–£1,000 (EGR cleaning or replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only

🟡 Monitor - book inspection soon

Our recommendation:

The EGR system on the B57 can become clogged with carbon deposits over time. Regular servicing and occasional Italian tune-ups can help. If you notice rough running or a drop in performance, have the EGR system inspected - cleaning it is far cheaper than replacing a failed EGR cooler.

3. Turbocharger Wastegate Actuator Wear

Symptoms: Rattling noise from the engine at low speeds or idle, noticeable drop in power, boost pressure loss.

Typical mileage: 60,000–100,000 miles

Repair cost: £800–£1,500 (wastegate actuator replacement) [PLACEHOLDER - confirm vs cost sheet]

Replacement cost: N/A - repair only (if caught before turbo damage)

🟠 Check - book inspection urgently if rattling or power loss occurs

Our recommendation:

The B57's twin-turbo setup delivers exceptional performance, but the wastegate actuator can wear over time. If you hear a rattling noise from the engine bay or notice a drop in power, have the turbo system inspected. Replacing a worn actuator is far cheaper than a full turbo replacement.

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M340d - 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.

M340d - 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 SenseDPF clogging✅ Yes£300–£800Routine maintenance - forced regen or cleanEGR carbon build-up✅ Yes£400–£1,000Routine maintenance - clean or replace valveWastegate actuator wear✅ Yes£800–£1,500Catch it early - before turbo damageAdBlue system faults✅ Yes£500–£1,500Often software - can be resolved; hardware faults require specialistSevere engine damage (timing chain / overheating)❌ Usually NoEngine replacementLittle left to salvage - replacement is the only option

Buying This M340d? Check These First

Buy If

Documented DPF regeneration history or regular long-distance driving
EGR system cleaned or replaced within the last 40,000 miles
No rattling from the turbo area - wastegate actuator in good condition
Full BMW service history with correct oil spec

Avoid If

DPF warning light with no regeneration history - may indicate heavy clogging
Rough idle with no EGR history - carbon build-up may be significant
Rattling from the engine bay - wastegate actuator may be failing
Engine warning light with no diagnosis - potentially expensive emissions system issues

Closing Verdict

The B57 is one of BMW's finest modern diesel engines - a 3.0-litre straight-six with 340 bhp, 700 Nm and genuine M‑lite performance. It's not without its watchpoints - DPF, EGR, wastegate actuator and AdBlue are the main areas to monitor - but it's fundamentally robust. Buy on full service history and pay attention to DPF health. A well‑maintained M340d is a long‑lived performance diesel.

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

→ Compare M340d engine prices before you buy

Don't Guess. Compare.

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

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Buying Checklist

Before you buy a used BMW 3 Series M340d (or before you commit to an engine replacement), check these:

DPF Status

Check for warning lights; short journeys can cause clogging

Cold Start

Listen for rattling; wastegate actuator wear indicator

Rough Idle

Check for uneven running; EGR carbon build-up possible

Service History

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

Coolant Level

Check for unexplained loss; EGR cooler or water pump may be failing

AdBlue System

Check for warning lights; AdBlue system faults are common

Oil Consumption

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

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.

B57D30T2 (3.0 straight-six twin-turbo)

Years2020–2022

Power340 bhp @ 4,400 rpm; 700 Nm @ 1,750–2,250 rpm

2025 Enquiries- (pattern data)

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

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

B57D30T2 (3.0 straight-six twin-turbo)2020–2022340 bhp @ 4,400 rpm; 700 Nm @ 1,750–2,250 rpm- (pattern data)£5,000–£7,500 [PLACEHOLDER]

B57D30T2 (3.0 straight-six twin-turbo, 48V MHEV)2022–present340 bhp @ 4,400 rpm; 700 Nm @ 1,750–2,250 rpm + 19 bhp e‑boost- (pattern data)£5,500–£8,000 [PLACEHOLDER]

Technical Specs

B57D30T2 3.0 straight-six diesel

Displacement2,993 cc

Cylinders6-cylinder inline

Compression Ratio16.5:1

Fuel SystemCommon-rail direct injection

TurbochargerTwin-turbo (Bi-Turbo)

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Market Intelligence

Most Common Failure

DPF clogging / EGR carbon build-up

the most frequently reported B57 issues

Average Enquiry Mileage

45,000

–65,000 miles

[PATTERN DATA]

Average Replacement Cost

£6,000

reconditioned, supply only

[PLACEHOLDER - confirm vs cost sheet]

Most Requested Engine Code

B57D30T2

[PATTERN DATA]

Peak Enquiry Season

Autumn/Winter

DPF and AdBlue issues exposed by colder weather

Regional Demand

South East19%

London17%

North West13%

PATTERN DATA

Regional Demand Breakdown

19%South East

17%London

13%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 3 Series M340d 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 performance diesel.

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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