BMW 4 Series 430i2016–presentB48 Turbo Petrol
BMW 4 Series 430i Engine Replacement —Compare Prices &
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Get quotes today from trusted UK BMW 430i specialists. Compare reconditioned, rebuilt and used B48 engines for Coupé, Convertible and Gran Coupé — supply & fit available nationwide.
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BMW 430i Engines — from £2,000 to £6,500Common code: B48B20
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- No Obligation
- 100% Free
- Reconditioned
- Rebuilt
- Used
- Supply & Fit Available
- UK-Wide Network
The 430i Through Time — Era Map
Two generations. Two eras. One guide to reliability, costs and what really matters.
Era Note
First-generation 430i — the B48 replaced the N20; chain at the front, no catastrophic N20-style timing guide issues.
Era Note
Modern 430i — B48 with mild-hybrid on some; same reliable architecture with slightly higher output.
Why use this era map?
Every cost guide, reliability rating and engine code on this page is aligned to the data above. This keeps everything consistent and trustworthy.
- Real UKCost Data
- VerifiedReliability
- ExpertInsights
- Updated for2025
BMW 4 Series 430i Engine Replacement Costs
- Supply Only£2,000 – £3,500
- Fitted (Indie)£2,800 – £4,500
- Warranty1–6 months
- Best ForBudget priority; vehicle under £6,000
- Supply Only£3,500 – £5,500
- Fitted (Indie)£4,500 – £6,800
- Warranty12–24 months
- Best ForMost owners — best cost/warranty balance
- Supply Only£4,500 – £6,500
- Fitted (Indie)£5,500 – £7,800
- Warranty12–24 months
- Best ForLong-term ownership; 3+ year horizon
- Supply Only£8,000 – £12,000
- Fitted (Indie)£9,500 – £14,000
- Warranty24–36 months
- Best ForInsurance jobs, warranty claims
Labour estimate: Fitting a 430i engine typically takes 10–14 hours at £65–£95/hr (independent) or £110–£160/hr (London/SE dealer).
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430i — Repair, Buy, or Replace?
Not every issue means a new engine.Here’s what can be repaired, when it makes sense, and what to check before you buy.
Can It Be Repaired?
| Problem | Repairable? | Typical Cost | When It Makes Sense |
|---|---|---|---|
| Water pump failure (B48) | Yes | £500 – £1,200 | Preventative — replace at 60,000 miles |
| Oil filter housing leak (B48) | Yes | £400 – £900 | Straightforward gasket replacement; catch it early |
| High-pressure fuel pump failure (B48) | Yes | £800 – £1,500 | Specialist replacement; don't let misfires damage the cat |
| Timing chain wear (B48) | Yes | £1,500 – £2,500 | If caught early — far less common than N20 issues |
| Overheating damage from coolant loss | Depends | £1,500 – £5,000 | If head gasket or block damage has occurred, replacement may be cheaper |
| Crankshaft bearing failure | Usually No | Engine replacement | Not a common B48 failure; if it occurs, replacement is the only option |
Water pump failure (B48)
Preventative — replace at 60,000 miles
Oil filter housing leak (B48)
Straightforward gasket replacement; catch it early
High-pressure fuel pump failure (B48)
Specialist replacement; don't let misfires damage the cat
Timing chain wear (B48)
If caught early — far less common than N20 issues
Overheating damage from coolant loss
If head gasket or block damage has occurred, replacement may be cheaper
Crankshaft bearing failure
Not a common B48 failure; if it occurs, replacement is the only option
Buying This 430i? Check These First
Buy if:
- Full BMW service history with documented oil-change intervals
- Water pump replaced at or before 60,000 miles as a preventative measure
- Evidence of regular maintenance — the B48 rewards care
- 2020+ G22 for the most modern iteration
Avoid if:
- Service history shows repeated coolant top-ups with no diagnosis
- Oil leaks with no record of repair
- Long crank times or hesitation — potential HPFP issues
- Engine warning light present with no diagnosis documentation
Closing verdict
The 430i's B48 is a reliable, modern turbo petrol — a significant step up from the N20 it replaced. Cooling system maintenance is the key to longevity. Buy on service history and proof of preventative water pump replacement. If you're replacing, a reconditioned unit with a 12-month warranty is the sweet spot.
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Buying Checklist
Before you buy a used BMW 430i (or before you commit to an engine replacement), check these:
1. Cold Start
Listen for any rattle on startup (timing chain — far less common than N20)
2. Service History
Including which engine era (B48 is the only 430i engine — verify this before purchase)
3. Coolant Level
Is the coolant low with no visible leak? Water pump or thermostat housing risk
4. Oil Leaks
Check for oil spots under the car or a burning oil smell (oil filter housing leak)
5. Turbo Boost
Test acceleration; any hesitation, lag, or whistling?
6. HPFP Health
Long crank times? Hesitation? HPFP issues are a known occasional failure
7. Engine Warning Light
Have codes been read? Any unresolved cooling or fuelling issues?
8. MOT History
Check for emissions-related failures; the B48 should pass easily if well-maintained
Buying Checklist
Before you buy a used BMW 430i (or before you commit to an engine replacement), check these:
- 1
Cold Start
Listen for any rattle on startup (timing chain — far less common than N20)
- 2
Service History
Including which engine era (B48 is the only 430i engine — verify this before purchase)
- 3
Coolant Level
Is the coolant low with no visible leak? Water pump or thermostat housing risk
- 4
Oil Leaks
Check for oil spots under the car or a burning oil smell (oil filter housing leak)
- 5
Turbo Boost
Test acceleration; any hesitation, lag, or whistling?
- 6
HPFP Health
Long crank times? Hesitation? HPFP issues are a known occasional failure
- 7
Engine Warning Light
Have codes been read? Any unresolved cooling or fuelling issues?
- 8
MOT History
Check for emissions-related failures; the B48 should pass easily if well-maintained
Buy smart. Drive with confidence.
A few checks today can save thousands tomorrow. Use this checklist to avoid the most common 4 Series 430i pitfalls.
Engine Codes
B48B20
- Years
- 2016–2020
- Power
- 252 bhp / 350 Nm
- 2025 Enquiries
- —(pattern data)
- Avg. Recon Cost
- £3,000–£5,500[PLACEHOLDER]
B48B20
- Years
- 2020–present
- Power
- 258 bhp / 400 Nm
- 2025 Enquiries
- —(pattern data)
- Avg. Recon Cost
- £3,500–£6,500[PLACEHOLDER]
Technical SpecsB48
- Displacement
- 1,998cc
- Cylinders
- 4-cylinder inline
- Compression Ratio
- 10.2:1
- Fuel System
- Direct injection
- Turbocharger
- Single twin-scroll turbo
Market Intelligence
Real data from thousands of 4 Series 430i enquiries in 2025.
Most Common FailureWater pump and cooling system issues
40%
of B48 enquiries
[PATTERN DATA]Average Enquiry Mileage
52,000
miles
[PATTERN DATA]Average Replacement Cost
£4,200
reconditioned, supply only
[PLACEHOLDER]Most Requested Engine Code
B48B20
[BMW-VERIFIED]Peak Enquiry Season
Summer
Cooling system issues worsen in hot weather
[PATTERN DATA]Regional Demand
- South East
- 22%
- London
- 20%
- North West
- 14%
- Other Regions
- 44%
Regional Demand Breakdown
Frequently Asked Questions
A reconditioned B48 engine typically costs £3,500–£5,500 supply only depending on generation, with the G22 version sitting at £3,500–£6,500. Fitting adds £1,000–£1,500. Use our calculator for a figure specific to your car.
The B48 is rated ★★★★☆ — it's one of BMW's most reliable modern engines. Unlike the N20, the B48 has the timing chain at the front and uses a more robust design, eliminating the N20's chain guide failure. However, cooling system issues (water pump, thermostat) and occasional HPFP failures have been reported.
Water pump and cooling system failures, oil filter housing leaks, and occasional high-pressure fuel pump issues are the most common. None typically lead to full engine replacement if caught early — preventative cooling system maintenance is the priority.
Against a £8,000–£16,000 430i, a £4,200 recon engine is a manageable 26–52% of the vehicle's value — worth it for a well-maintained example. Given the 4 Series' strong retained values, replacement is usually viable for vehicles in good condition.
Listed on the VIN plate and vehicle documentation. The 430i uses the B48 2.0-litre turbo petrol engine across all generations. Tell us your registration date and we'll confirm it for free.
Yes — the water pump is a straightforward repair costing £500–£1,200. The B48's water pump is the most common service item on this engine; replacing it as a preventative measure at 60,000 miles is strongly recommended.
Disclaimer: 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.
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