BMW 4 Series G22Coupé2020–present
Engine Database
Every engine fitted to the G22 Coupé — spanning B48 four-cylinder petrols, B58 straight-six petrols, B47 four-cylinder diesels, and B57 straight-six diesels, all with eight-speed automatic transmission.
Overview
The G22 is the second generation of the BMW 4 Series Coupé, unveiled in June 2020 as the successor to the F32. It shares the CLAR platform with the G20 3 Series and features a longer wheelbase, wider track, and the controversial vertical kidney grille that defines this generation's design language.
The engine line-up is all-turbocharged, featuring B48 four-cylinder petrols, B58 straight-six petrols (with 48V mild-hybrid assistance on the M440i), B47 four-cylinder diesels, and B57 straight-six diesels (both with mild-hybrid technology). A significant 2024 LCI (Life Cycle Impulse) facelift brought updated power outputs, mild-hybrid electrification to more variants, and the BMW Curved Display with Operating System 8.5.
Key Facts
Market Intelligence
The G22 4 Series Coupé generated 120+ real UK engine enquiries in 2025 [BMW-VERIFIED], concentrated on the 420i petrol and 420d diesel as the range reaches the used market.
04Best & Worst Engines
Best Petrol Overall
B58B30 (M440i xDrive, 374–387 bhp, MHEV)
“BMW's B58 straight-six is widely regarded as the most reliable modern BMW engine. Smooth, responsive, and with 48V mild-hybrid assistance for seamless stop-start. The M440i offers effortless performance with 374 bhp and 500 Nm of torque, making it the pinnacle of the G22 petrol range.”
Who it's for: enthusiasts who want the ultimate G22 experience.
Best Diesel Overall
B57D30 (M440d xDrive, 340 bhp, MHEV)
“The most powerful diesel in the G22 range — 340 bhp and 700 Nm of torque from a 3.0-litre straight-six diesel with mild-hybrid assistance. Refined, effortless, and surprisingly efficient for its performance level.”
Who it's for: buyers who want diesel torque with six-cylinder refinement.
Highest Risk
B47D20 (420d, 190 bhp, MHEV)
“The B47 is significantly more reliable than the N47 it replaced, but diesel emission components (EGR cooler, DPF, AdBlue) remain a potential cost. The mild-hybrid system adds complexity versus non-hybrid alternatives.”
Who it's for: buyers who prioritise fuel economy and are willing to maintain the diesel system carefully.
Most Expensive Failure
B58B30 (M440i xDrive)
“The B58 is the most expensive engine to replace in the G22 range — a full reconditioned unit can exceed £7,000. Cooling system leaks and oil filter housing failures are the primary concerns.”
Who it's for: buyers who want six-cylinder performance and have warranty cover.
Best Value
B48B20B (420i, 184 bhp)
“The entry-level petrol is the smart buy for most UK buyers — 184 bhp is more than adequate for daily driving, the B48 is proven and reliable, and running costs are significantly lower than the six-cylinder options. The 420i offers the best blend of performance, efficiency and value in the G22 range.”
Who it's for: buyers who want coupé style with sensible running costs.
Most Overlooked
B48B20B (430i, 245–258 bhp)
“The 430i sits between the 420i and M440i — and it's the sweet spot for many buyers. With 245–258 bhp and 400 Nm of torque, it's quicker than the 420i (0-62 mph in 5.8 seconds vs 7.5) without the M440i's six-cylinder running costs. The post-LCI 430i with 258 bhp is particularly impressive.”
Who it's for: buyers who want strong performance without the M440i's premium.
Best Petrol Overall
B58B30
(M440i xDrive, 374–387 bhp, MHEV)
“BMW's B58 straight-six is widely regarded as the most reliable modern BMW engine. Smooth, responsive, and with 48V mild-hybrid assistance for seamless stop-start. The M440i offers effortless performance with 374 bhp and 500 Nm of torque, making it the pinnacle of the G22 petrol range.”
Who it's for: enthusiasts who want the ultimate G22 experience.
Best Diesel Overall
B57D30
(M440d xDrive, 340 bhp, MHEV)
“The most powerful diesel in the G22 range — 340 bhp and 700 Nm of torque from a 3.0-litre straight-six diesel with mild-hybrid assistance. Refined, effortless, and surprisingly efficient for its performance level.”
Who it's for: buyers who want diesel torque with six-cylinder refinement.
Highest Risk
B47D20
(420d, 190 bhp, MHEV)
“The B47 is significantly more reliable than the N47 it replaced, but diesel emission components (EGR cooler, DPF, AdBlue) remain a potential cost. The mild-hybrid system adds complexity versus non-hybrid alternatives.”
Who it's for: buyers who prioritise fuel economy and are willing to maintain the diesel system carefully.
Most Expensive Failure
B58B30
(M440i xDrive)
“The B58 is the most expensive engine to replace in the G22 range — a full reconditioned unit can exceed £7,000. Cooling system leaks and oil filter housing failures are the primary concerns.”
Who it's for: buyers who want six-cylinder performance and have warranty cover.
Best Value
B48B20B
(420i, 184 bhp)
“The entry-level petrol is the smart buy for most UK buyers — 184 bhp is more than adequate for daily driving, the B48 is proven and reliable, and running costs are significantly lower than the six-cylinder options. The 420i offers the best blend of performance, efficiency and value in the G22 range.”
Who it's for: buyers who want coupé style with sensible running costs.
Most Overlooked
B48B20B (430i, 245–258 bhp)
“The 430i sits between the 420i and M440i — and it's the sweet spot for many buyers. With 245–258 bhp and 400 Nm of torque, it's quicker than the 420i (0-62 mph in 5.8 seconds vs 7.5) without the M440i's six-cylinder running costs. The post-LCI 430i with 258 bhp is particularly impressive.”
Who it's for: buyers who want strong performance without the M440i's premium.
Engine
Typical Mileage
Common Major Failure
Repair Cost (Specialist)
Replacement Cost (Recon)
Ownership Verdict
Safe Bet -proven B48, reliable.
Best Petrol -the most robust six-cylinder.Solid Choice -improved over N47.Solid Choice -refined and powerful.EngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership VerdictSafe Bet -proven B48, reliable.Best Petrol -the most robust six-cylinder.Solid Choice -improved over N47.Solid Choice -refined and powerful.
The G22 rule
A £2,800–£5,000 B47 recon against a £15,000–£40,000 G22 sits at 7–33% of the car's value【EM-VERIFIED】. Even on a lower-value example, that's well within our 70% BMW scrap threshold -replacement is almost always viable. The G22's strong retained values mean engine replacement is a repair decision, not a financial one. For M440i cars (£25,000–£45,000+), even the most expensive replacement is comfortably viable.
Key Takeaways
Which G22 Costs Least To Own?
B48 420i -simple four-cylinder, proven reliability, lower running costs.
Which G22 Costs Most To Own?
B58 M440i -six-cylinder running costs and higher replacement cost.
Which G22 Is Best Value?
B48 430i -strong performance, proven B48 reliability, and the sweet spot of the range.
B48
/ B58 Cooling System Leaks (Oil Filter Housing)
Affected models:
G22 420i, 430i, M440i (B48/B58 engines).
Typical failure mileage:
40,000–80,000 miles.
Root cause:
The oil filter housing on B48 and B58 engines is a known weak point -the insert in one of the oil filter housing channels is made from a material that cannot withstand constant temperature changes, leading to coolant leaks. Coolant can leak from the oil filter housing and coolant vent pipe. If ignored, this can lead to overheating and engine damage.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500
£500–£1,000
Oil filter housing replacement, coolant system flush
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£3,800–£7,000
Full engine replacement if overheating caused damage
Our Recommendation
Have the cooling system inspected annually and investigate any coolant loss immediately -a £500–£1,000 oil filter housing replacement is dramatically cheaper than the £3,800+ engine replacement that follows if ignored. Check for coolant stains under the car or a sweet smell in the cabin.
B48
/ B58 Water Pump Failure
Affected models:
G22 420i, 430i, M440i (B48/B58 engines).
Typical failure mileage:
80,000–100,000 miles.
Root cause:
The electric water pump on B48 and B58 engines can fail prematurely -this is a known weakness across BMW's B-family engines. Failure leads to sudden overheating and potential engine damage.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£600–£1,200
£400–£800
Water pump and thermostat replacement
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£3,800–£7,000
Full engine replacement if overheating caused damage
Our Recommendation
Replace the water pump as preventative maintenance at 80,000 miles -a £400–£800 specialist job is trivial against the £3,800+ engine replacement that follows an ignored overheating event.
B47
/ B57 Diesel EGR Cooler & Emission System Issues
Affected models:
G22 420d, 430d, M440d (B47/B57 engines).
Typical failure mileage:
60,000–120,000 miles.
Root cause:
The B47 and B57 diesel engines can suffer from EGR cooler failure -internal leaks allow coolant to enter the exhaust system. DPF clogging (urban driving) and AdBlue system issues are also common. BMW has issued recalls for EGR cooler issues on some models.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500 (recall may cover)
£500–£1,000
EGR cooler replacement, DPF clean, AdBlue system service
Catastrophic (Replacement)
Dealer
Specialist
£5,000–£8,000
£4,500–£7,500
Full engine replacement if coolant contamination caused damage
Our Recommendation
Check your diesel G22's VIN against any outstanding EGR cooler recalls -if affected, the repair is free. For DPF health, ensure regular motorway driving to allow regeneration cycles to complete. Have the emission system inspected at 60,000 miles.
G22
48V Mild-Hybrid System Issues
Affected models:
G22 M440i, 420d, 430d, M440d (48V MHEV-equipped variants).
Typical failure mileage:
40,000–80,000 miles.
Root cause:
The 48V mild-hybrid system adds complexity -the 48V battery, starter-generator, and associated electronics can develop issues. The 48V battery typically has a lifespan of 5–8 years.
Tiered Cost Table
Preventative (Repair)
Dealer
Specialist
£800–£1,500
48V battery health check, system diagnostics
Catastrophic (Replacement)
Dealer
Specialist
£3,500–£5,500
48V battery and/or starter-generator replacement
Our Recommendation
Have the 48V system inspected during annual servicing -a £500–£1,000 check is cheap insurance against a £2,800+ system replacement. The mild-hybrid system improves efficiency and refinement -protect it.
VariantEngine Code
Used (Supply)
Reconditioned (Supply)
Rebuilt (Supply)
Labour HoursNo Generation variance from the EM_Proprietary_Data baseline figures -G22 4 Series shares the CLAR platform with the G20 3 Series, with similar engine-bay access, so costs are inherited directly per the Authority Model, with no divergence note required.
Diesel Variants
Petrol Variants
Scope note: All variants listed are G22 Coupé only. G23 Convertible and G26 Gran Coupé share the same engine families but are covered on their own Generation Pages. M440i, 420d, 430d and M440d feature 48V mild-hybrid technology. 430i power output increased from 245 bhp to 258 bhp with the 2024 LCI facelift.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£4,200
reconditioned, supply only
[BMW-QUOTE]
Most Common Failures
Live FeedBMW 4 Series
G22 420i
London
Coolant leak inspection3
enquiries
Updated MonthlyBMW 4 Series
G22 M440i
ManchesterWater pump replacement2
enquiries
Updated MonthlyBMW 4 Series
G22 420d
BirminghamEGR cooler recall check2
enquiries
Updated MonthlyMost Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£4,200
reconditioned, supply only
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£4,200
reconditioned, supply only
[BMW-QUOTE]
Most Common Failures
Diesel Variants
Petrol Variants
Scope note: All variants listed are G22 Coupé only. G23 Convertible and G26 Gran Coupé share the same engine families but are covered on their own Generation Pages. M440i, 420d, 430d and M440d feature 48V mild-hybrid technology. 430i power output increased from 245 bhp to 258 bhp with the 2024 LCI facelift.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£4,200
reconditioned, supply only
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£4,200
reconditioned, supply only
[BMW-QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£4,200
reconditioned, supply only
[BMW-QUOTE]
Most Common Failures
Live FeedBMW 4 Series
G22 420i
LondonCoolant leak inspection3
enquiries
BMW 4 Series
G22 M440i
ManchesterWater pump replacement2
enquiries
BMW 4 Series
G22 420d
BirminghamEGR cooler recall check2
enquiries
Updated MonthlyTrusted G22 Engine Suppliers
every garage and engine rebuilder in our network is vetted, rated and reviewed by real 4 Series owners, as part of the Engine Finders network.
Compare G22 Engine Replacement Companies
see prices, warranty terms and supply & fit options side-by-side before you commit.
UK Engine Replacement Services for G22
covering every variant from 420i to M440d, with supply-only or full supply & fit available nationwide.
Find the best BMW 4 Series G22 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today and get back on the road with confidence.
Compare BMW 4 Series G22 Engine Prices on EnginesMarket