How much does a BMW 5 Series 520i engine replacement cost in the UK-

A BMW 5 Series 520i engine replacement typically costs £1,500-£3,600 supply-only for rebuilt units, or £2,800-£5,500 fitted by a specialist. Prices vary by engine code and generation. Used N46B20 engines: £800-£1,400 supply-only. Used N20B20 engines: £1,200-£1,900 supply-only. Reconditioned B48B20 units: £2,200-£3,200 supply-only. Rebuilt N20B20 units: £2,200-£3,400 supply-only. Professional fitting adds £800-£1,500 depending on workshop location.

Which engine does the BMW 5 Series 520i have - N46, N20 or B48-

The 520i badge spans three engine families depending on the generation: E60 520i (2003-2010): N46B20, 150-170hp, naturally aspirated. F10 520i (2010-2016): N20B20, 184hp, turbocharged. G30 520i (2017-present): B48B20, 184hp, turbocharged, closed-deck block. G60 520i (2023-present): B48B20, 208hp, 48V mild hybrid.

Is the BMW 5 Series 520i N20 engine reliable- I've heard about timing chain problems.

The N20B20 is a capable engine, but early units (pre-2015) are prone to timing chain guide degradation between 40,000-70,000 miles. The problem is caused by plastic guides that become brittle under heat cycling. Timing chain rattle on cold start is the first warning sign. Preventative chain replacement costs £1,400-£1,900 at a specialist. Post-2015 N20 units received revised guide materials. B48 engines in G30 models have largely resolved timing chain concerns.

What are the signs of cooling system failure on a BMW 5 Series 520i B48-

The B48 engine's most common cooling system issues include coolant level drops without visible external leaks, coolant vent line cracking (between cylinder head and expansion tank), oil filter housing cracking causing coolant loss, warning lights on the dashboard, and overheating if coolant loss is ignored.

Is it worth replacing the engine on a high-mileage BMW 5 Series 520i-

For an F10 520i worth £4,000-£8,000, a rebuilt N20 at £2,200-£3,400 can make financial sense if the body, gearbox, and interior are in good condition. For G30 examples, replacement is generally viable given higher retained values. Compare replacement cost against vehicle value - replacement is viable up to 70% of car's value. F10 520i values have stabilised; a good example justifies investment. B48 engines in G30 command higher value - replacement more easily justified. Always factor 12-month warranty into replacement decision.

Can I replace my N20 engine with a B48 in my BMW 5 Series 520i-

While both are 2.0-litre turbo petrol engines, swapping an N20 for a B48 is not straightforward and is rarely cost-effective: different engine mounts, wiring harness, and ECU calibration. B48 requires different cooling system components. DME coding and immobiliser adaptation required. Specialist verification essential before ordering.

BMW 520i SPECIALISTS

BMW 5 Series 520i Engine Replacement Compare Prices & Get Quotes

Get quotes today from trusted UK BMW 5 Series 520i engine specialists. Compare prices on reconditioned, rebuilt and used 2.0-litre turbo petrol engines for the E60, F10 and G30 520i - supply & fit available nationwide.

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BMW 5 Series 520i Engine

from£1,500 to £3,600

Usedfrom £1,200
Reconditionedfrom £1,800
Common codesN46B20, N20B20, B48B20

BMW 5-seriesUsed Engine — N46B20

BMW 5-series 520i Reconditioned Engine — N46B20

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BMW 5-series 520i Rebuilt Engine — N46B20

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How it works

3 Simple Steps to Finding the Right Replacement Engine

Clear information first, then the right engine and specialist for your exact vehicle.

Variant History

BMW 5 Series 520i Engine History & Specs at a Glance

The BMW 5 Series 520i has been the entry-level petrol variant across three generations of the executive saloon. From the naturally aspirated N46B20 in the E60, through the turbocharged N20B20 in the F10, to the modern B48B20 in the G30, the 520i badge has consistently delivered accessible four-cylinder petrol power with BMW's signature rear-wheel-drive dynamics and executive refinement.

2003
E60 520i launched with N46B20 2.0-litre naturally aspirated four-cylinder, 150-170hp, Valvetronic
2007
E60 LCI updates N46B20 with minor ECU calibration changes
2010
F10 520i debuts with N20B20 2.0-litre turbocharged four-cylinder, 184hp, TwinPower Turbo
2016
F10 LCI continues with N20B20; B48B20 introduced in G30 520i, 184hp, closed-deck block
2020
G30 LCI updates B48B20 with 48V mild hybrid, 184hp, improved efficiency
2023
G60 520i launched with B48B20, 208hp, 48V mild hybrid

Every engine fitted to the BMW 5 Series 520i is covered below, with UK rebuilt pricing and known failure points specific to each 2.0-litre petrol generation.

Engine Codes & Pricing

BMW 5 Series 520i Engine Codes Specifications & Replacement Cost

Find your exact engine code, specs and UK replacement cost guide.

N46B20 — 2.0L Naturally Aspirated Petrol (2003-2010)

Power Output: 150-170hp (110-125kW) @ 6,200rpm
Torque: 200-210Nm @ 3,600rpm
Displacement: 1,995cc
Years Fitted: 2003-2010 (E60 520i)
Engine Features: Naturally aspirated inline-four, Valvetronic, DOHC 16-valve, aluminium block

Can’t find your exact engine code?-> Get quotes for N46B20 BMW 5 Series 520i engine replacement

-> Get quotes for N46B20 BMW 5 Series 520i engine replacement

Common Problems

BMW 5 Series 520i What It Costs to Fix, and When Replacement Makes Sense

The BMW 5 Series 520i has evolved from the naturally aspirated N46 to the turbocharged N20 and the modern B48, each with its own well-documented wear patterns. The N20 engine family drives the highest volume of replacement enquiries due to early timing chain guide degradation, while the B48 suffers from cooling system weaknesses. Every rebuilt engine supplied through EnginesMarket includes upgraded components designed to address these original failure points - plus a minimum 12-month unlimited mileage warranty.

Common failure points and repair options

Timing Chain Guide Failure

Affected: BMW 5 Series 520i (F10 2010-2016, N20B20)
Typical failure mileage: 40,000-70,000 miles

Root cause

The N20's plastic timing chain guides degrade under heat cycling, leading to chain slack, rattling on cold start, and eventual chain slip or snap. If ignored, the chain can skip teeth, allowing pistons to contact valves - catastrophic engine failure requiring full replacement.

Repair options

Repair tier	Dealer price	Specialist price
Preventative - Timing Chain & Tensioner Kit	£2,500-£3,500	£1,400-£1,900
Full Replacement - rebuilt/reconditioned engine	£4,500-£6,500	£2,200-£3,400

Our recommendation

If your F10 520i develops a cold-start rattle that disappears as the engine warms, act immediately - preventative chain replacement saves thousands. Once the chain snaps, the engine is beyond economic repair. Frequent oil changes (every 8,000-10,000 miles) are critical for N20 longevity.

-> Compare rebuilt N20B20 engine prices for your BMW 5 Series 520i

Coolant System Failure

Affected: BMW 5 Series 520i (G30 2017-present, B48B20)
Typical failure mileage: 40,000-70,000 miles

Root cause

The B48's plastic coolant vent line between the cylinder head and expansion tank can crack, causing rapid coolant loss. The oil filter housing can also crack, leaking coolant into the engine bay.

Repair options

Repair tier	Dealer price	Specialist price
Coolant Vent Line & Expansion Tank Replacement	£500-£800	£300-£500
Oil Filter Housing Replacement	£800-£1,200	£450-£700
Full Replacement - rebuilt/reconditioned engine	£4,000-£6,000	£2,600-£3,600

Our recommendation

The B48 is generally reliable, but cooling system issues are its Achilles' heel. Check coolant levels monthly and address any drops immediately. A £300-£500 specialist vent line replacement is cheap insurance against a warped cylinder head. On any G30 520i approaching 60,000 miles without documented cooling system work, proactive inspection is strongly advised.

-> Compare BMW 5 Series 520i B48 cooling system repair costs

Oil Leaks

Affected: BMW 5 Series 520i (E60 2003-2010 N46B20, F10 2010-2016 N20B20, G30 2017-present B48B20)
Typical failure mileage: 50,000-90,000 miles

Root cause

The valve cover gasket and oil filter housing gasket become brittle with age and heat cycling, allowing oil to seep onto the engine or exhaust components.

Repair options

Repair tier	Dealer price	Specialist price
Gasket Replacement	£500-£800	£300-£550
Full Replacement - rebuilt/reconditioned engine	£4,000-£6,500	£2,200-£3,600

Our recommendation

Oil leaks on the 520i's four-cylinder engines are common but rarely catastrophic if addressed promptly. Check for oil around the valve cover and oil filter housing regularly. A £300-£550 specialist gasket replacement is cheap insurance against a more serious oil starvation issue.

-> Compare BMW 5 Series 520i oil leak repair costs

Don't Let Engine Failure Write Off Your BMW 5 Series 520i

A failed N46, N20 or B48 doesn't have to mean the end of the road for your 520i. Whether you're facing timing chain guide failure on the N20, cooling system issues on the B48, or oil leaks on any generation, EnginesMarket connects you with trusted UK BMW petrol specialists who supply rebuilt engines with upgraded components specifically designed to address the original failure points. Every engine comes with a minimum 12-month unlimited mileage warranty, nationwide delivery, and supply & fit options across the UK. Compare prices today - and get back on the road without paying the main dealer premium.

Compare BMW 5 Series 520i Engine Replacement Prices Now ->

FAQ

BMW 5 Series 520i Engine ReplacementFrequently Asked Questions

Everything BMW 5 Series 520i owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

A BMW 5 Series 520i engine replacement typically costs £1,500-£3,600 supply-only for rebuilt units, or £2,800-£5,500 fitted by a specialist. Prices vary by engine code and generation.

Used N46B20 engines: £800-£1,400 supply-only
Used N20B20 engines: £1,200-£1,900 supply-only
Reconditioned B48B20 units: £2,200-£3,200 supply-only
Rebuilt N20B20 units: £2,200-£3,400 supply-only
Professional fitting adds £800-£1,500 depending on workshop location

-> Compare BMW 5 Series 520i engine replacement prices from UK specialists

The N20B20 is a capable engine, but early units (pre-2015) are prone to timing chain guide degradation between 40,000-70,000 miles. The problem is caused by plastic guides that become brittle under heat cycling.

Timing chain rattle on cold start is the first warning sign
Preventative chain replacement costs £1,400-£1,900 at a specialist
Post-2015 N20 units received revised guide materials
B48 engines in G30 models have largely resolved timing chain concerns

-> Get quotes for BMW 5 Series 520i N20 timing chain replacement

For an F10 520i worth £4,000-£8,000, a rebuilt N20 at £2,200-£3,400 can make financial sense if the body, gearbox, and interior are in good condition. For G30 examples, replacement is generally viable given higher retained values.

Compare replacement cost against vehicle value - replacement is viable up to 70% of car's value
F10 520i values have stabilised; a good example justifies investment
B48 engines in G30 command higher value - replacement more easily justified
Always factor 12-month warranty into replacement decision

-> Check BMW 5 Series 520i engine replacement value for your specific model year

While both are 2.0-litre turbo petrol engines, swapping an N20 for a B48 is not straightforward and is rarely cost-effective:

Different engine mounts, wiring harness, and ECU calibration
B48 requires different cooling system components
DME coding and immobiliser adaptation required
Specialist verification essential before ordering

-> Get compatibility advice for your BMW 5 Series 520i engine replacement

Why Choose Us

Compare BMW 5 Series 520i Engine Prices Today

Comparing quotes for your BMW 5 Series 520i is free, no-obligation, and specific to your exact executive saloon and its engine code - N46B20, N20B20, or B48B20. Whether you need a used replacement, a reconditioned unit, or a full rebuilt engine with upgraded components, our network of trusted UK BMW petrol specialists delivers transparent pricing and nationwide coverage. Don't let a failed engine end the life of the UK's favourite executive saloon - compare prices today and get back on the road with confidence.

11,000+11,000+ BMW 5 Series engines supplied through our network, including 520i variants

12-Month12-Month Warranty on every rebuilt 520i engine

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Compare quotes from trusted UK BMW 5 Series 520i engine specialists with warranty-backed rebuilt, reconditioned and used options nationwide.

BMW 5 Series 520i Engine Replacement Compare Prices & Get Quotes

Get your free BMW 5-series 520i engine quotes

3 Simple Steps to Finding the Right Replacement Engine

BMW 5 Series 520i Engine History & Specs at a Glance

BMW 5 Series 520i Engine Codes Specifications & Replacement Cost

N46B20 — 2.0L Naturally Aspirated Petrol (2003-2010)

BMW 5 Series 520i What It Costs to Fix, and When Replacement Makes Sense

Timing Chain Guide Failure

Coolant System Failure

Oil Leaks

Don't Let Engine Failure Write Off Your BMW 5 Series 520i

BMW 5 Series 520i Engine ReplacementFrequently Asked Questions

Compare BMW 5 Series 520i Engine Prices Today