How much does a BMW 850CSi engine replacement cost in the UK?

A reconditioned S70B56 V12 engine typically costs £10,000–£16,000 supply only - and that's if you can find one. Only 1,510 were ever built. Fitting adds £2,000–£4,000 depending on your location and workshop. A full specialist rebuild is often the most practical option for CSi owners. Main dealer new engines are no longer available. Use our calculator for a figure specific to your car.

Is the BMW 850CSi engine reliable?

The S70B56 is a robust engine, but it's also a complex, 12-cylinder BMW from the 1990s. Common issues include DK throttle motor failure, MAF sensor and intake hose deterioration, and ignition system problems. With proper maintenance from a specialist, these engines can be very reliable - but they are not cheap to maintain. The engine itself is less of a concern than the age-related degradation of rubber and electronic components.

What are the common problems with the BMW 850CSi?

The most frequently reported issues are DK throttle motor failure (erratic idle, hesitation, EML light), MAF sensor failure (flat spots, poor throttle response), cracked rubber intake hoses (unmetered air, rough running), and ignition system failures (coils, distributor rotors, plugs). These are all age-related issues common to complex 1990s BMWs.

Is it worth replacing a BMW 850CSi engine, or should I scrap the car?

This depends entirely on the car's condition. A well-maintained 850CSi is now worth £60,000–£100,000+, making a £15,000 engine replacement a sound investment. Against a tired example needing other work, the maths changes. These cars are appreciating rapidly - only 1,510 were built worldwide, with just 160 right-hand drive examples - so a proper restoration is often justified. Get a specialist inspection before committing.

How do I find my BMW 850CSi engine code?

Listed on the VIN plate and vehicle documentation. The 850CSi carries the engine code S70B56 (also referred to as S70 B56). It's a 5.6-litre V12 naturally aspirated engine, used exclusively in the E31 850CSi from 1992 to 1996. You can identify the S70B56 by the 'Powered by M' inscription on the central cam cover between the two banks of cylinders.

Can I repair the DK throttle motors, or do they need replacement?

Yes - DK throttle motor repair is a well-understood specialist job costing £800–£2,000. Rebuilding the existing motors is often more cost-effective than replacing them. If you experience erratic idle, hesitation, or EML warning lights, have the DK motors inspected immediately. Ignoring throttle motor issues can lead to more serious engine problems.

BMW 850CSi1992–19965.6L V12 (S70B56)

BMW 850CSi Engine Replacement — Compare Prices & Get Quotes

Name: BMW 850CSi UK Engine Enquiry Data 2025
Creator: BMWEngines.uk

Get quotes today from trusted UK BMW 8 Series specialists. Compare reconditioned, rebuilt and used S70B56 V12 engines - the most powerful engine BMW had built up to that point - supply & fit available nationwide.

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BMW 850CSi Engines - from £8,000 to £18,000Common code: S70B56

BMW 850CSi Engines - from £8,000 to £18,000· Common code: S70B56

Instant QuotesNo Obligation100% FreeReconditionedRebuiltUsedSupply & Fit AvailableUK-Wide Network

The 850CSi THROUGH TIME - Era Map

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

Era Note

One engine throughout this badge's history - no era ambiguity. Only 1,510 units ever built.

GenerationYearsEngine CodeReliabilityRecon CostEra Note

E31 850CSi BMW 320d E31 850CSi

1992–1996S70B56 (5.6L V12)★★★☆☆ [NEWLY ASSIGNED - see Data Note]£10,000–£16,000 [PLACEHOLDER - confirm vs cost sheet]One engine throughout this badge's history - no era ambiguity. Only 1,510 units ever built.

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 850CSi Engine Replacement Costs

Supply Only£10,000–£16,000

Fitted (Indie)£12,000–£18,500

Warranty12–24 months

Best ForMost owners - best cost/warranty balance; specialist rebuild required

Engine TypeSupply OnlyFitted (Indie)WarrantyBest For

Used Engine£6,000–£10,000£8,000–£12,5001–6 monthsBudget priority; extremely rare - sourcing an engine is the challenge

Reconditioned Engine£10,000–£16,000£12,000–£18,50012–24 monthsMost owners - best cost/warranty balance; specialist rebuild required

Rebuilt Engine£12,000–£18,000£14,000–£20,50012–24 monthsLong-term ownership; 3+ year horizon; concours restoration

Main Dealer NewN/AN/AN/ANo longer available from BMW - the S70B56 has been out of production for decades

Figures above reflect the S70B56 V12 engine. Only 1,510 S70B56 engines were ever built, making sourcing a replacement extremely difficult and expensive. A complete engine rebuild by a specialist is typically the most cost-effective option for a CSi owner. Prices above are estimates only - actual costs vary enormously depending on availability.

Labour estimate: Fitting an 850CSi engine typically takes 20–30 hours at £80–£120/hr (independent specialist) or £150–£200/hr (London/SE dealer). The V12's complexity and the car's tight engine bay make this a labour-intensive job.

→ Compare 850CSi engine prices from UK specialists

Common Problems With BMW 320d Engines

1. DK Throttle Motor Failure

Symptoms: Erratic idle, hesitation on acceleration, flat spots in the throttle response, EML warning light, engine cutting out when returning to idle when hot.

Typical mileage: 50,000–100,000 miles

Repair cost: £800–£2,000 (DK motor replacement or rebuild)【PLACEHOLDER - confirm vs cost sheet】

Replacement cost: £8,000–£18,000 (if left untreated and leads to engine damage)

🟠 Check - book inspection urgently

Our recommendation:

The DK throttle motors are a known weak point on the S70B56. If you experience erratic idling or hesitation, have the throttle motors inspected. Replacement or rebuild is expensive but far cheaper than engine replacement. This is one of the most common issues on the 850CSi.

Read the full throttle motor failure guide

1. DK Throttle Motor Failure

Symptoms: Erratic idle, hesitation on acceleration, flat spots in the throttle response, EML warning light, engine cutting out when returning to idle when hot.

Typical mileage: 50,000–100,000 miles

Repair cost: £800–£2,000 (DK motor replacement or rebuild)【PLACEHOLDER - confirm vs cost sheet】

Replacement cost: £8,000–£18,000 (if left untreated and leads to engine damage)

🟠 Check - book inspection urgently

Our recommendation:

Read the full throttle motor failure guide

2. MAF Sensor & Intake Hose Deterioration

Symptoms: Flat spots in acceleration, erratic throttle response, lack of power, engine warning light, rough idle.

Typical mileage: 60,000–120,000 miles

Repair cost: £300–£800 (MAF sensor replacement or cleaning; intake hose replacement)【PLACEHOLDER - confirm vs cost sheet】

Replacement cost: N/A - repair only

🟡 Monitor - book inspection soon

Our recommendation:

The rubber intake hoses between the airflow meters and throttle valves can crack with age, causing unmetered air to enter the engine. Dirty or failed MAF sensors can also cause flat spots. Regular inspection and replacement of ageing rubber components is essential on these cars.

Read the full MAF sensor failure guide

3. Ignition System Failures (Coils, Distributor Rotors, Plugs)

Symptoms: Engine coughing or skipping under acceleration, subtle shake at idle, misfires, loss of power.

Typical mileage: 60,000–120,000 miles

Repair cost: £400–£1,200 (coil packs, distributor rotors, spark plugs)【PLACEHOLDER - confirm vs cost sheet】

Replacement cost: N/A - repair only

🟡 Monitor - book inspection soon

Our recommendation:

The S70B56's 12-cylinder ignition system has 12 individual coils, two distributors, and 12 spark plugs. Over time, coils can fail, distributor rotors can corrode and seize, and plugs can wear. Replacing ignition components is a routine maintenance item on these cars - but with 12 cylinders, it's more expensive than on a six-cylinder. If you notice hesitation or misfires, have the ignition system inspected.

Read the full ignition system failure guide

Weighing Your Options?

Compare Specialist Quotes When You're Ready

20+ vetted BMW specialists, every 850CSi V12 era covered, with a 12-month warranty as standard.

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850CSi - 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.

850CSi - 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 SenseDK throttle motor failure✅ Yes£800–£2,000Specialist rebuild or replacement - far cheaper than engine replacementMAF sensor failure✅ Yes£300–£800Straightforward replacement; keeps engine running correctlyIntake hose deterioration✅ Yes£200–£600Replace ageing rubber hoses - essential maintenanceIgnition system issues✅ Yes£400–£1,200Routine maintenance on a 12-cylinder; keep on top of itMajor internal engine failure⚠️ Sometimes£8,000–£18,000Often more cost-effective to rebuild than replace - but still eye-wateringly expensive

Buying This 850CSi? Check These First

Buy If

Full documented service history from a BMW V12 specialist
DK throttle motors replaced or recently serviced
MAF sensors and intake hoses inspected and replaced if necessary
Ignition system (coils, distributors, plugs) serviced within the last 20,000 miles
No EML or engine warning lights

Avoid If

EML or engine warning lights with no documented diagnosis
Erratic idle or hesitation with no DK throttle motor history
Poor service history - the S70B56 is a complex engine that demands specialist care
Evidence of overheating or cooling system issues

Closing Verdict

The 850CSi is a true BMW icon - the most powerful BMW up to that point, powered by a magnificent S70B56 V12, and produced in tiny numbers (only 1,510 worldwide, with just 160 right-hand drive examples). It's a future classic that's already appreciating rapidly. But it's also a complex, 12-cylinder BMW from the 1990s - and maintenance costs reflect that. DK throttle motors, MAF sensors, ignition components, and rubber hoses all need attention. Buy on documented history, not on faith - and budget for specialist maintenance. A well-maintained 850CSi is a £60,000–£100,000+ investment; a neglected one is a £15,000 repair bill waiting to happen.

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

→ Compare 850CSi 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 850CSi engine prices before you buy

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Buying Checklist

Before you buy a used BMW 850CSi (or before you commit to an engine replacement), check these:

Cold Start

Listen for smooth idle; any hesitation or erratic behaviour? (DK throttle motor warning)

Service History

including the S70B56 era (1992–1996) and confirmed specialist maintenance

EML Warning Light

Any history of EML or engine warning lights? (DK motor, MAF, or ignition issues)

Throttle Response

Test acceleration; any flat spots or hesitation? (DK motor or MAF warning)

Idle Quality

Any shaking, stumbling, or erratic idle? (DK motor or ignition system warning)

Ignition System

Have coils, distributor rotors, and plugs been replaced recently?

Intake Hoses

Have the rubber intake hoses been inspected or replaced? (ageing rubber is a common issue)

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.

S70B56 (5.6L V12)

Years1992–1996

Power380 PS (279 kW / 375–380 hp) @ 5,300 rpm · 550 Nm (406 lb-ft) @ 4,000 rpm

2025 Enquiries- (pattern data)

Avg. Recon Cost£10,000–£16,000 [PLACEHOLDER - confirm vs cost sheet]

Engine CodeYearsPower2025 EnquiriesAvg. Recon Cost

S70B56 (5.6L V12)1992–1996380 PS (279 kW / 375–380 hp) @ 5,300 rpm · 550 Nm (406 lb-ft) @ 4,000 rpm- (pattern data)£10,000–£16,000 [PLACEHOLDER - confirm vs cost sheet]

Technical Specs

S70B56

Displacement5,576 cc (5.6L)

CylindersV12, 2 valves per cylinder (24 valves total)

Compression Ratio9.8:1

Fuel SystemBosch Motronic electronic fuel injection

AspirationNaturally aspirated

Transmission6-speed manual Getrag 560G (exclusively)

ProductionOnly 1,510 units ever built

→ Compare 850CSi engine prices for your BMW

Get quotes from trusted UK specialists in minutes.

Market Intelligence

Most Common Failure

DK throttle motor failure

a known weak point on the S70B56

Average Enquiry Mileage

50,000

–80,000 miles

[PATTERN DATA]

Average Replacement Cost

£10,000

–£16,000 reconditioned, supply only

[PLACEHOLDER - confirm vs cost sheet]

Most Requested Engine Code

S70B56

[PATTERN DATA]

Peak Enquiry Season

Spring/Summer

classic car season exposes issues after winter storage【PATTERN DATA】

Regional Demand

South East22%

London20%

South West15%

PATTERN DATA

Regional Demand Breakdown

22%South East

20%London

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.

Why UK BMW 850CSi Owners Trust BMWEngines.uk

Trusted 850CSi V12 Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real 8 Series owners, as part of the Engine Finders network, with specialist experience in BMW's flagship V12 engines - including the rare S70B56.
Compare 850CSi Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit, across every E31 that left the factory with this magnificent 5.6-litre V12.
UK Engine Replacement Services for 850CSi
supply-only or full supply & fit available nationwide, covering the full E31 production run - and we're vetted across every era of this badge, including the ultra-rare 850CSi.

Find the best BMW 850CSi engine replacement UK drivers rely on. Compare prices from trusted specialists on EnginesMarket today and get your 8 Series back on the road with confidence.

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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