How much does a BMW 3 Series G21 engine replacement cost in the UK?

A reconditioned G21 engine typically costs £2,500–£8,000 supply only [BMW-QUOTE], depending on engine -the B48 four-cylinder sits at £2,800–£5,200, the B58 straight-six at £4,500–£8,000, and the 330e PHEV at £4,000–£7,000. Fitting adds £650–£1,170. Use our calculator for a personalised figure.

Which BMW 3 Series G21 engine is the most reliable?

The B48 2.0-litre four-cylinder petrol in 320i form (184 bhp) is the most reliable G21 engine -it's proven across BMW's CLAR platform, avoids the complexity of the 330e's hybrid system or the diesel's DPF considerations, and offers strong performance for a sensible price. The B58 straight-six is also highly robust.

What are the common problems with the BMW 3 Series G21?

Common issues include: cooling system failures (water pump, thermostat) on the B48 and B58 petrol engines; timing chain wear on higher-mileage B47 diesels; DPF clogging on diesel variants used primarily for short urban trips; and battery degradation on the 330e plug-in hybrid.

Is the BMW 3 Series G21 reliable?

Overall, yes -the G21's B48 and B58 petrol engines are modern and highly reliable. The B47 diesel is significantly more robust than its N47 predecessor. The 330e PHEV is more complex but well-supported. The M340i's B58 is reliable but places additional strain on the cooling system.

Which G21 engine should I avoid?

We don't recommend outright avoidance -but a B47 diesel without regular service history, particularly if used for short urban trips where DPF clogging is more likely, is one to approach with caution. For the 330e, ensure the battery health is documented and the cooling system is in good condition.

How do I know if my G21 engine needs replacing?

Key warning signs: B48/B58 -coolant loss with no external leak, overheating, or water pump noise; B47 -timing chain rattle on cold start, DPF warning light, or loss of power; 330e -reduced electric range, battery warning lights, or cooling system faults. Use our diagnostic guide to identify the specific symptoms.

How long do BMW 3 Series G21 engines last?

The B48 and B58 petrols can exceed 150,000 miles with proper servicing. The B47 diesel is robust and can reach 150,000+ miles with regular maintenance. The 330e's battery health is the limiting factor -expect 8–10 years of service before significant degradation.

What is the difference between the G20, G21, G80 and G81?

The G20 is the seventh-generation 3 Series saloon (2019–present). The G21 is the Touring (estate) variant (2019–present). The G80 is the M3 saloon (2020–present). The G81 is the M3 Touring (2023–present). All share the CLAR platform but have different engine lineups -the G21 Touring shares its engines with the G20 saloon.

How do I find my BMW 3 Series G21 engine code?

Listed on the VIN plate and vehicle documentation; block stamping varies by engine. For the B48, the code is on the block near the exhaust manifold. For the B58 and B57, it's on the block face below the inlet manifold. Tell us your registration and we'll identify it -20+ vetted BMW specialists will confirm it for free.

BMW 3 Series G21Touring2019–2025

BMW 3 Series G21 Engines — The Complete UK Guide

Every engine fitted to the G21 Touring — from the 2.0-litre four-cylinder petrols and diesels to the 3.0-litre straight-six M340i and the 330e plug-in hybrid.

Real UK replacement costs, honest failure data, and the coolant system and timing chain issues that define this generation's ownership story.

Backed by real UK enquiry data [PATTERN DATA].

Explore G21 Engines

G21 Enquiries (Pattern Data)
Touring
7+Engine Codes
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G21 Enquiries (Pattern Data)
TouringBody Style
7+Engine CodesCovered
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Engine Database

BMW 3 Series G21 Engine Codes — The Complete Database

Every engine fitted to the G21 Touring — from the 2019 launch to the present, including the 2022 LCI updates and the 2024 diesel phase-out.

Engine CodeFuelPowerYearsReliabilityEnquiries (2025)Avg. Recon Cost

B48B20A / B48B20BB48PetrolTurbo184 bhp2019–present★★★★☆PROVISIONALpending dedicated Engine Page—(pattern data)£2,800–£4,800[BMW-QUOTE]

B48B20BB48PetrolTurbo258 bhp2019–present★★★★☆PROVISIONALpending dedicated Engine Page—(pattern data)£3,000–£5,200[BMW-QUOTE]

B58B30BB58PetrolTurbo374 bhp2019–present★★★★☆PROVISIONALpending dedicated Engine Page—(pattern data)£4,500–£8,000[BMW-QUOTE]

B48B20 (PHEV)B48Petrol PHEV292 bhp(combined)2020–present★★★☆☆PROVISIONALpending dedicated Engine Page—(pattern data)£4,000–£7,000[BMW-QUOTE]

B47D20BB47DieselTurbo150 bhp2019–2024★★★☆☆PROVISIONALpending dedicated Engine Page930JLR-wideBMW-VERIFIED£2,500–£4,500[BMW-QUOTE]

B47D20BB47DieselTurbo190 bhp2019–2024★★★☆☆PROVISIONALpending dedicated Engine Page930JLR-wideBMW-VERIFIED£2,800–£4,800[BMW-QUOTE]

B57D30AB57DieselTurbo265 bhp2019–2024★★★★☆PROVISIONALpending dedicated Engine Page830JLR-wideBMW-VERIFIED£3,500–£6,000[BMW-QUOTE]

Overview

BMW 3 Series G21 — Overview

The G21 is the Touring (estate) variant of the seventh-generation BMW 3 Series, launched in 2019 as the successor to the F31 Touring. It shares the CLAR platform with the G20 saloon and offers the same range of four-cylinder and six-cylinder petrol and diesel engines, plus the 330e plug-in hybrid.

A 2022 facelift (LCI) brought updated styling and technology, while 2024 saw the removal of diesel options from the UK line-up. The range-topping M340i xDrive produces 374 bhp from its B58 straight-six, and the M3 Touring (G81) sits above as the performance flagship.

Key Facts

PlatformBMW CLAR (Cluster Architecture)
PredecessorF31
SuccessorTBA
Sibling Body Styles in this GenerationG20 (saloon), G80 (M3 saloon), G81 (M3 Touring)

Market Intelligence

The G21 Touring remains a popular choice in the UK premium estate segment, with strong demand for the 320i petrol and 330e plug-in hybrid variants [PATTERN DATA].

04Best & Worst Engines

Best & Worst Engines

Thin-Data Summary

Thin-Data Fallback mode — exactly one paragraph: The B58 3.0-litre straight-six in the M340i xDrive is the jewel of the G21 range — 374 bhp, smooth, sonorous, and one of BMW's most reliable modern engines. The B48 2.0-litre four-cylinder petrol in 320i form (184 bhp) is the sensible choice: proven, efficient, and free from the complexity of the 330e's hybrid system or the diesel's DPF considerations. The 330e plug-in hybrid offers excellent company-car tax benefits and strong performance (292 bhp), but its hybrid system adds complexity and potential battery costs. The B47 diesels are robust and economical, but their UK availability ended in 2024. For most buyers, the 320i petrol strikes the best balance of performance, reliability, and running costs.

Thin-Data Summary

BMW 3 Series G21
Ownership Economics

Engine

Typical Mileage

Common Major Failure

Repair Cost (Specialist)

Replacement Cost (Recon)

Ownership Verdict

B48B20 (320i)60k–120kCooling system; water pump£300–£800£2,800–£4,800

Best Petrol -proven, reliable, and the sensible choice.

B48B20 (330i)60k–120kCooling system; water pump£300–£800£3,000–£5,200

Strong Choice -more power, same reliable architecture.

B58B30 (M340i)60k–120kCooling system; oil leaks£400–£1,000£4,500–£8,000

Performance Choice -reliable but expensive to replace.

B48 PHEV (330e)40k–80kBattery degradation; cooling system£500–£1,500£4,000–£7,000

Tax-Efficient Choice -complex but well-supported.

B47D20 (320d)60k–120kTiming chain wear; DPF£500–£1,200£2,800–£4,800

High-Mileage Choice -robust but discontinued in UK.

B57D30 (330d)60k–120kTiming chain wear; DPF£500–£1,200£3,500–£6,000

Diesel Six -torquey and refined, but discontinued.

Engine

Typical Mileage

Common Major Failure

Repair Cost (Specialist)

Replacement Cost (Recon)

Ownership Verdict

B48B20 (320i)60k–120kCooling system; water pump£300–£800£2,800–£4,800

Best Petrol -proven, reliable, and the sensible choice.

B48B20 (330i)60k–120kCooling system; water pump£300–£800£3,000–£5,200

Strong Choice -more power, same reliable architecture.

B58B30 (M340i)60k–120kCooling system; oil leaks£400–£1,000£4,500–£8,000

Performance Choice -reliable but expensive to replace.

B48 PHEV (330e)40k–80kBattery degradation; cooling system£500–£1,500£4,000–£7,000

Tax-Efficient Choice -complex but well-supported.

B47D20 (320d)60k–120kTiming chain wear; DPF£500–£1,200£2,800–£4,800

High-Mileage Choice -robust but discontinued in UK.

B57D30 (330d)60k–120kTiming chain wear; DPF£500–£1,200£3,500–£6,000

Diesel Six -torquey and refined, but discontinued.

The G21 rule

A £4,800 B48 recon against a £25,000 G21 sits at 19% -well within our 70% BMW threshold. Even the M340i's £8,000 recon against a £35,000 car is just 23%. Unlike older BMWs, the G21's high retained value means engine replacement is almost always financially viable. Value the car first -but on a modern G21, a recon is usually a repair decision, not a financial one.

Key Takeaways

Which G21 Costs Least To Own?
320i -proven reliability, reasonable running costs, and no hybrid complexity.
Which G21 Costs Most To Own?
M340i xDrive -higher fuel consumption, more complex drivetrain, and higher replacement costs.
Which G21 Is Best Value?
320i -the sweet spot of performance, reliability, and running costs.

Common Problems

B48

Cooling System Failure

Affected models:

G21 320i, 330i (2019–present).

Typical failure mileage:

60,000–100,000 miles.

Root cause:

The B48 four-cylinder petrol engine suffers from water pump failure and cooling system leaks. The plastic coolant pipes and thermostat housing can become brittle with age and heat cycling, leading to coolant loss and potential overheating.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£700–£1,200

£400–£900

Water pump replacement; coolant system inspection

Yes -routine maintenance

Catastrophic (Replacement)

Dealer

Specialist

£4,000–£6,500

£2,800–£4,800

Full reconditioned B48 engine

Often 15–25% of G21 value

Our Recommendation

Have the cooling system inspected at every service -a £400–£900 water pump replacement is far cheaper than the £2,800–£4,800 engine replacement that follows an overheating failure.

Compare B48 engine prices for your G21

B58

Cooling System and Oil Leak Issues

Affected models:

G21 M340i xDrive (2019–present).

Typical failure mileage:

60,000–100,000 miles.

Root cause:

The B58 straight-six is generally robust, but oil leaks from the oil filter housing and valve cover gasket can occur. The cooling system is complex and can develop leaks at the coolant expansion tank and hoses.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£800–£1,500

£500–£1,200

Oil leak repair; cooling system inspection

Yes -cheap insurance

Catastrophic (Replacement)

Dealer

Specialist

£5,500–£9,000

£4,500–£8,000

Full reconditioned B58 engine

Often 15–25% of G21 value

Our Recommendation

On any M340i approaching 60,000 miles, have the cooling system and oil filter housing inspected -a £500–£1,200 preventative repair is far cheaper than the £4,500–£8,000 replacement that follows a major failure.

Compare B58 engine prices for your G21

B47

Diesel Timing Chain and DPF Issues

Affected models:

G21 318d, 320d (2019–2024).

Typical failure mileage:

60,000–120,000 miles.

Root cause:

The B47 diesel is significantly more robust than its N47 predecessor, but timing chain wear can still occur on higher-mileage cars with neglected servicing. DPF clogging from short urban trips is also a common issue.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£1,000–£2,000

£600–£1,500

Timing chain inspection; DPF cleaning

Yes -cheap insurance

Catastrophic (Replacement)

Dealer

Specialist

£4,500–£7,000

£2,800–£4,800

Full reconditioned B47 engine

Often 15–25% of G21 value

Our Recommendation

On any B47 diesel approaching 60,000 miles, have the timing chain inspected and ensure the DPF is regularly regenerated with motorway driving. A £600–£1,500 preventative service is far cheaper than the £2,800–£4,800 replacement that follows a chain failure.

Compare B47 engine prices for your G21

330e

PHEV Battery and Cooling System Issues

Affected models:

G21 330e, 330e xDrive (2020–present).

Typical failure mileage:

40,000–80,000 miles.

Root cause:

The 330e's plug-in hybrid system adds complexity -battery degradation over time, cooling system leaks, and charging system faults can occur. The battery's 19.5 kWh capacity provides up to 63 miles of electric range, but battery health is critical to the car's value.

Tiered Cost Table

Preventative (Repair)

Dealer

Specialist

£1,000–£2,500

£600–£1,500

Battery health check; cooling system service

Yes -routine maintenance

Catastrophic (Replacement)

Dealer

Specialist

£8,000–£12,000

£6,000–£9,000

Full battery module replacement

Often 25–40% of G21 value

Our Recommendation

On any 330e approaching 40,000 miles, have the battery health checked and the cooling system inspected -a £600–£1,500 preventative service is far cheaper than the £6,000–£9,000 battery replacement that follows a major failure.

Compare 330e battery and engine prices for your G21

G21
Engine Replacement Costs -By Engine and Condition

Variant

Engine Code

Used (Supply)

Reconditioned (Supply)

Rebuilt (Supply)

Labour Hours

320iB48B20A / B48B20B£1,500–£2,800£2,800–£4,800£4,000–£6,50010–14 hrs

330iB48B20B£1,800–£3,200£3,000–£5,200£4,500–£7,00010–14 hrs

M340i xDriveB58B30B£2,500–£4,500£4,500–£8,000£6,500–£10,00014–18 hrs

330e / 330e xDriveB48 PHEV£2,200–£3,800£4,000–£7,000£6,000–£9,00014–18 hrs

318dB47D20B£1,200–£2,500£2,500–£4,500£3,800–£6,00010–14 hrs

320d / 320d xDriveB47D20B£1,500–£2,800£2,800–£4,800£4,000–£6,50010–14 hrs

330d / 330d xDriveB57D30A£2,000–£3,500£3,500–£6,000£5,500–£8,00012–16 hrs

No Generation variance note required -no Engine Page baseline exists for these engines yet. Costs are sourced from UK specialist suppliers [BMW-QUOTE].

Diesel & Petrol Lineup

Diesel Variants

Petrol Variants

Scope note: All variants listed are BMW 3 Series Touring G21 only. The G20 saloon, G80 M3 saloon and G81 M3 Touring are separate models with different engine availability and are covered on their own pages. Diesel variants were removed from the UK line-up in 2024.

Market Intelligence

Most Requested Engines (2025)

Most Requested Variants

Average Replacement Cost

Most Common Failures

Most Requested Engines (2025)

Most Requested Variants

Average Replacement Cost

Most Common Failures

Most Requested Engines (2025)

Most Requested Variants

Average Replacement Cost

Most Common Failures

Diesel & Petrol Lineup

Diesel Variants

Petrol Variants

Market Intelligence

Most Requested Engines (2025)

Most Requested Variants

Average Replacement Cost

Most Common Failures

Most Requested Engines (2025)

Most Requested Variants

Average Replacement Cost

Most Common Failures

Most Requested Engines (2025)

Most Requested Variants

Average Replacement Cost

Most Common Failures

FAQ

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Compare BMW 3 Series G21 Engine Prices on EnginesMarket

BMW 3 Series G21 Engines — The Complete UK Guide

BMW 3 Series G21 Engine Codes — The Complete Database

BMW 3 Series G21 — Overview

Best & Worst Engines

BMW 3 Series G21 Ownership Economics

Common Problems

G21Engine Replacement Costs -By Engine and Condition

Diesel & Petrol Lineup

Market Intelligence

Diesel & Petrol Lineup

Market Intelligence

FAQ

Why UK BMW 3 Series G21 OwnersTrust BMWEngines.uk

BMW 3 Series G21
Ownership Economics

G21
Engine Replacement Costs -By Engine and Condition

Why UK BMW 3 Series G21 Owners
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