BMW M135i Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK BMW M135i engine specialists. Compare prices on reconditioned, rebuilt and used N55B30 engines for the F20/F21 M135i - supply & fit available nationwide.
Supply & Fit Available
12-Month Warranty
Nationwide Delivery
100+ Suppliers
From £4,000 to £6,500
Used from £1,800 · Reconditioned from £3,200 · Common codes: N55B30
From £1,800
Tested, bare/short engine
From £3,200
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
Secure enquiry - no spam, no pressure. Genuine quotes only from vetted UK BMW M135i specialists.
3 Simple Steps3 Simple Stepsto Finding the Best BMW M135i Replacement Engineto Finding the Best BMW M135i Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryBMW M135i - Engine History & Specs at a Glance
The BMW M135i (F20/F21) launched in 2012 as the first M Performance model in the 1 Series range, powered by a 3.0-litre turbocharged straight-six N55 engine that delivered 320 hp and 450 Nm of torque.
Variant HistoryBMW M135i - Engine History & Specs at a Glance
The BMW M135i (F20/F21) launched in 2012 as the first M Performance model in the 1 Series range, powered by a 3.0-litre turbocharged straight-six N55 engine that delivered 320 hp and 450 Nm of torque.
BMW M135i
Fuel TypePetrol
Engine Size Range3.0L
Power Output Range320-326 hpEngine History Timeline
N55B30 3.0L turbocharged straight-six, 320 hp, launch of the F20/F21 M135i with rear-wheel drive
LCI (Life Cycle Impulse) update; power output increased to 326 hp in some markets
M135i production ends; replaced by the BMW M140i with the B58 engine
Key Specs Snapshot
Fuel TypePetrolEngine Size Range3.0LPower Output Range320-326 hpYears Produced2012-2015Every engine fitted to the BMW M135i is covered below, with UK rebuilt pricing and known failure points.
BMW M135i Engine Codes - Specifications & Replacement CostBMW M135i Engine Codes - Specifications & Replacement Cost
3.0L Petrol (2012-2015)
Power Output320-326 hpYears Fitted2012-2015
Compatible Trim Levels
- M135i
- M135i M Sport
- M135i xDrive (2013-2015)
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,800-£3,200
Reconditioned
Addressed known issues, tested
£3,200-£4,500
Rebuilt
Full teardown, upgraded internals
£4,000-£6,500
Common Failure
The N55 engine is prone to oil leaks from the valve cover gasket, oil filter housing gasket, and oil pan gasket. High-pressure fuel pump (HPFP) failure and turbocharger wastegate rattle are also well-documented issues.
The BMW M135i's N55B30 turbocharged straight-six is a strong performer, but it has well-documented vulnerabilities. Oil leaks, HPFP failure, and wastegate rattle are the most common issues driving replacement demand. Every rebuilt engine supplied through EnginesMarket includes upgraded gaskets and components designed to address the original failure points - plus a minimum 12-month unlimited mileage warranty.
Valve Cover, Oil Filter Housing & Oil Pan Gaskets
Affected Vehicles
BMW M135i (N55B30, 2012-2015)
Typical Failure Mileage
50,000-90,000 miles
Root Cause
The N55 engine's gaskets degrade over time due to heat cycling, leading to oil leaks from the valve cover, oil filter housing, and oil pan.
Why It Happens
The N55 engine's gaskets degrade over time due to heat cycling, leading to oil leaks from the valve cover, oil filter housing, and oil pan.
Dealer (parts + labour)
£600-£1,200
Specialist (parts + labour)
£400-£800
What it involves
Replacement of the failed gasket (valve cover, oil filter housing, or oil pan)
Suitability
Adds 50k-80k miles. Viable if caught early
1 - 2 daysDealer (parts + labour)
£1,200-£2,500
Specialist (parts + labour)
£800-£1,600
What it involves
Replacement of all common leak points simultaneously
Suitability
80k+ mile lifespan. Cheaper long-term than doing one at a time
1 - 2 daysDealer (parts + labour)
£7,000-£10,000
Specialist (parts + labour)
£4,000-£6,500
What it involves
Complete rebuilt engine with new gaskets, seals, and upgraded components
Suitability
Required if oil starvation caused bottom-end damage
1 - 2 daysAll prices are indicative UK market ranges based on current UK specialist supplier data.| Repair Tier | Dealer (Parts + Labour) | Specialist (Parts + Labour) | What It Involves | Suitability | Estimated Time |
|---|---|---|---|---|---|
 Minor - Gasket Replacement (single) Minor | £600-£1,200 | £400-£800 | Replacement of the failed gasket (valve cover, oil filter housing, or oil pan) | Adds 50k-80k miles. Viable if caught early | 1 - 2 days |
 Intermediate - Multiple Gasket Replacement Best Value | £1,200-£2,500 | £800-£1,600 | Replacement of all common leak points simultaneously | 80k+ mile lifespan. Cheaper long-term than doing one at a time | 1 - 2 days |
Full Replacement - Rebuilt N55B30 Best Value | £7,000-£10,000 | £4,000-£6,500 | Complete rebuilt engine with new gaskets, seals, and upgraded components | Required if oil starvation caused bottom-end damage | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
Apply this UK-wide decision framework, substituting the BMW M135i-appropriate value band from research: - Vehicle worth under ~£5,000: repair or used engine typically makes more sense than a full rebuilt unit. - Vehicle worth ~£5,000-£8,000: evaluate both; reconditioned is viable if keeping the car 2+ years. - Vehicle worth ~£8,000-£15,000: reconditioned/rebuilt usually justifies the premium via warranty and reliability. - Vehicle worth £15,000+: replacement cost is typically small relative to vehicle value. A typical BMW M135i of relevant age (2012-2015) sits in the £5,000-£12,000 band, so a rebuilt engine is generally viable.
Our Recommendation
Our Recommendation
If you catch oil leaks early, a gasket replacement is cost-effective. However, if the engine has been driven with low oil pressure or the leaks have been ignored for extended periods, debris may have contaminated the bottom end - in which case a full rebuilt unit with upgraded gaskets is the safer long-term investment.
Don't Let Engine Failure Write Off Your BMW M135i
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific BMW M135i. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
Compare rebuilt N55B30 BMW M135i engine prices
12-Month Minimum
UK Specialists Vetted
Best Price GuidanceImportant Information
Important Information
"All prices are indicative UK market ranges based on historical quote data and repair requests from our network of engine specialists. Dealer pricing is estimated based on published main dealer labour rates and genuine OEM parts pricing. Specialist pricing reflects actual quote data from EnginesMarket's UK network. Actual costs vary depending on damage severity, vehicle condition, variant, and workshop location within the UK. Use our free comparison tool to get tailored quotes for your specific BMW M135i. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW M135i Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW M135i engine replacement cost in the UK-
A rebuilt N55B30 engine for the BMW M135i typically costs £4,000-£6,500 supply-only. A reconditioned unit is £3,200-£4,500, while a used engine is £1,800-£3,200. Supply & fit adds £600-£1,200 depending on the specialist and location.
- Rebuilt: £4,000-£6,500 (supply only)
- Reconditioned: £3,200-£4,500 (supply only)
- Used: £1,800-£3,200 (supply only)
- Labour: £600-£1,200 extra for supply & fit
Question 2What are the common signs of N55 engine failure in a BMW M135i-
The most common warning signs include oil leaks (valve cover, oil filter housing, oil pan), long cranking times or rough idling (HPFP failure), and a rattling noise from the turbocharger at low speeds (wastegate rattle).
- Oil spots under the car or burning oil smell
- Check engine light with fuel system codes
- Rattling noise on deceleration or light load
Question 3Is it worth replacing the engine in a BMW M135i-
A BMW M135i of relevant age (2012-2015) typically sits in the £5,000-£12,000 value band. A rebuilt N55B30 engine costs £4,000-£6,500, which is a significant but justifiable investment - especially when the alternative is selling a non-running car at a massive loss.
- A non-running M135i sells for 30-50% of market value
- A rebuilt engine includes upgraded components the factory never fitted
- A documented specialist rebuild adds value to discerning buyers
Question 4How long does a rebuilt BMW M135i engine last-
A correctly rebuilt N55B30 engine using upgraded gaskets and components should last 100,000+ miles - often longer than the factory original. All engines supplied through EnginesMarket carry a minimum 12-month unlimited mileage warranty.
- Specialist rebuilds include upgraded gaskets and seals
- Upgraded components address the original failure points
- 12-month unlimited mileage warranty standard
Question 5What's the difference between the BMW M135i and BMW M140i engines-
The M135i uses the N55B30 3.0L turbocharged straight-six (320 hp), while the M140i uses the B58B30 3.0L turbocharged straight-six (340 hp). The B58 is a more modern engine with improved reliability and tuning potential, but the N55 remains a strong performer when properly maintained.
- M135i (2012-2015): N55B30, 320 hp, single twin-scroll turbo
- M140i (2015-2019): B58B30, 340 hp, improved design
- Both are straight-six petrol engines
Question 6Can I fit a used BMW M135i engine from a breaker, or should I buy rebuilt-
A used N55B30 engine is cheaper (£1,800-£3,200) but carries the same factory flaws that caused the original failure - oil leaks, HPFP issues, and wastegate rattle. A rebuilt engine costs more but eliminates those weaknesses with upgraded components.
- Used engine: cheaper but same factory weaknesses
- Rebuilt engine: more expensive but failure points addressed
- All rebuilt engines include 12-month warranty
Why Choose UsCompare BMW M135iEngine PricesToday
100+ M135i engines supplied through our network
12-Month Warranty on every rebuilt BMW M135i engine
Nationwide UK delivery
supply & fit available
Comparing quotes for your BMW M135i engine replacement is free, no-obligation, and specific to your exact engine code (N55B30) and variant. Join thousands of UK drivers who compare prices through our network of trusted specialists - every rebuilt and reconditioned unit backed by a minimum 12-month unlimited mileage warranty.
Enter your registration
and get matched with verified BMW M135i specialists.