BMW 1 Series M135i Engine ReplacementCompare Prices & Get Quotes
Get quotes today from trusted UK BMW 1 Series M135i engine specialists. Compare prices on reconditioned, rebuilt and used engines for your BMW M135i - the 320 hp N55 turbocharged straight-six that defined the modern M Performance hatchback. Covering the N55B30 engine across the F20 and F21 generations from 2012 to 2016.
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From £3,500 to £8,000+
Used from £1,800 · Reconditioned from £3,500 · Common codes: N55B30A, N55B30O0
From £1,800
Tested, bare/short engine
From £3,500
Rod bearings addressed, tested
From quote
Upgraded bearings, full teardown, revised valvetrain
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3 Simple Steps3 Simple Stepsto Finding the Best BMW 1 Series M135i Replacement Engineto Finding the Best BMW 1 Series M135i Replacement Engine
Most replacements completed within 3-5 days.
Variant HistoryBMW 1 Series M135i - Engine History & Specs at a Glance
The BMW M135i was launched in 2012 as the first M Performance model in the 1 Series range, sitting above the 135i and below the full-fat 1M Coupe. Powered by a 3.0-litre N55 turbocharged straight-six producing 320 hp, it combined rear-wheel-drive dynamics with genuine hot-hatch performance - 0-62 mph in 4.9 seconds (automatic) and a 155 mph limited top speed. The M135i represented BMW's answer to the Audi RS3 and Mercedes A45 AMG, offering a more engaging, rear-driven alternative. Production ran from 2012 to 2016 across the F20 (five-door) and F21 (three-door) body styles, before being replaced by the M140i with the B58 engine.
Variant HistoryBMW 1 Series M135i - Engine History & Specs at a Glance
The BMW M135i was launched in 2012 as the first M Performance model in the 1 Series range, sitting above the 135i and below the full-fat 1M Coupe. Powered by a 3.0-litre N55 turbocharged straight-six producing 320 hp, it combined rear-wheel-drive dynamics with genuine hot-hatch performance - 0-62 mph in 4.9 seconds (automatic) and a 155 mph limited top speed. The M135i represented BMW's answer to the Audi RS3 and Mercedes A45 AMG, offering a more engaging, rear-driven alternative. Production ran from 2012 to 2016 across the F20 (five-door) and F21 (three-door) body styles, before being replaced by the M140i with the B58 engine.
BMW 1 Series M135i
Fuel TypePetrol
Engine Size3.0L (2,979 cc)
Power Output320 hp (235 kW) @ 5,800 rpmEngine History Timeline
N55B30O0 3.0L single twin-scroll turbo straight-six, 320 hp (235 kW), launched with the F20 five-door and F21 three-door 1 Series
8-speed automatic transmission option introduced alongside the manual
F20/F21 LCI (Life Cycle Impulse) update; M135i continues with N55 engine producing 320 hp
M135i replaced by M140i with B58 engine producing 340 hp; the M135i badge is retired
Key Specs Snapshot
Fuel TypePetrolEngine Size3.0L (2,979 cc)Power Output320 hp (235 kW) @ 5,800 rpmTorque450 Nm @ 1,300-4,500 rpmYears Produced2012-2016Every engine fitted to the BMW 1 Series M135i is covered below, with UK rebuilt pricing and known failure points.
BMW 1 Series M135i Engine Codes - Specifications & Replacement CostBMW 1 Series M135i Engine Codes - Specifications & Replacement Cost
3.0L Turbocharged Petrol (2012-2016)
Power Output320 hp (235 kW) @ 5,800 rpmTorque450 Nm @ 1,300-4,500 rpmDisplacement2,979 ccBore x Stroke84 mm x 89.6 mmCompression Ratio10.2:1Years Fitted2012-2016
Compatible Trim Levels
- M135i
- M135i M Performance (F20 five-door, F21 three-door)
Find your exact engine code, specs and UK replacement cost guide.
Used
Tested, ready-to-fit engine
£1,800-£2,800
Reconditioned
Addressed known issues, tested
£3,500-£5,500
Rebuilt
Full teardown, upgraded internals
£4,500-£8,000
Main dealer new engine estimate
Tested, ready-to-fit engine
£12,000-£18,000 (parts only)
Common Failure
The N55 is generally more reliable than its predecessor, the twin-turbo N54, but common issues include valve cover gasket leaks, oil filter housing gasket leaks, electric water pump failure, VANOS solenoid failure, and charge pipe failure (particularly on tuned examples). Timing chain failure is incredibly rare on the N55, unlike the N47 and N20.
The BMW 1 Series M135i is powered exclusively by the N55B30 engine - a 3.0-litre single twin-scroll turbocharged straight-six that produces 320 hp and 450 Nm of torque. The N55 is generally regarded as reliable, with far fewer major failure points than the twin-turbo N54 it replaced. However, like all modern BMW engines, it has its common issues - primarily oil leaks, cooling system components, and charge pipe failures. Replacement demand for the BMW M135i is lower than for four-cylinder BMWs, but when failures occur, the cost of repair can be significant. Every rebuilt engine supplied through EnginesMarket includes upgraded components and a minimum 12-month unlimited-mileage warranty.
Valve Cover, Oil Filter Housing and VANOS Solenoid Seals
Affected Vehicles
BMW 1 Series M135i (N55B30, 2012-2016)
Typical Failure Mileage
50,000-100,000 miles
Root Cause
The N55 engine uses gaskets and seals that can become brittle and leak over time. The valve cover gasket, oil filter housing gasket, and VANOS solenoid seals are the most common leak points. A leaking valve cover gasket can cause oil to drip onto the exhaust manifold, producing a burning smell and smoke.
Why It Happens
The N55 engine uses gaskets and seals that can become brittle and leak over time. The valve cover gasket, oil filter housing gasket, and VANOS solenoid seals are the most common leak points. A leaking valve cover gasket can cause oil to drip onto the exhaust manifold, producing a burning smell and smoke.
Dealer (parts + labour)
£700-£1,000
Specialist (parts + labour)
£400-£650
What it involves
Replace valve cover gasket and PCV components
Suitability
Cost-effective if caught early
1 - 2 daysDealer (parts + labour)
£600-£900
Specialist (parts + labour)
£350-£550
What it involves
Replace oil filter housing gasket
Suitability
Address oil leaks before they cause further issues
1 - 2 daysDealer (parts + labour)
£500-£800
Specialist (parts + labour)
£300-£500
What it involves
Replace VANOS solenoid seals
Suitability
If VANOS-related fault codes are present
1 - 2 daysDealer (parts + labour)
£6,000-£9,000
Specialist (parts + labour)
£4,500-£8,000
What it involves
Complete rebuilt unit with new gaskets and seals
Suitability
If significant damage has occurred
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 |
|---|---|---|---|---|---|
 Valve Cover Gasket Replacement Minor | £700-£1,000 | £400-£650 | Replace valve cover gasket and PCV components | Cost-effective if caught early | 1 - 2 days |
 Oil Filter Housing Gasket Replacement Best Value | £600-£900 | £350-£550 | Replace oil filter housing gasket | Address oil leaks before they cause further issues | 1 - 2 days |
VANOS Solenoid Seal Replacement Best Value | £500-£800 | £300-£500 | Replace VANOS solenoid seals | If VANOS-related fault codes are present | 1 - 2 days |
Full Replacement - rebuilt engine Best Value | £6,000-£9,000 | £4,500-£8,000 | Complete rebuilt unit with new gaskets and seals | If significant damage has occurred | 1 - 2 days |
Vehicle Value Check
Vehicle Value Check
A typical 2012-2016 BMW 1 Series M135i is currently valued at approximately £8,000-£18,000 depending on mileage, condition and specification. This places the M135i firmly in the bracket where a rebuilt engine is a viable investment - replacement cost is typically small relative to vehicle value. For well-maintained, lower-mileage examples worth £12,000+, a reconditioned or rebuilt engine with warranty is a sound investment. For cars worth under £8,000 with catastrophic engine failure, evaluate scrap value first.
Our Recommendation
Our Recommendation
The N55 is a reliable engine, and oil leaks are the most common issue. Address gasket leaks promptly - a £350-£650 specialist repair is far cheaper than dealing with the consequences of a major oil leak. If you notice white smoke or a burning smell, have the valve cover gasket inspected immediately. Unlike the N20, the N55 does not have widespread timing chain issues, making it a more dependable choice for long-term ownership.
Don't Let Engine Issues Write Off Your BMW 1 Series M135i
The N55 engine in your BMW M135i is one of BMW's most celebrated turbocharged straight-sixes - a reliable, characterful engine that deserves proper maintenance. Oil leaks, Valvetronic wear and water pump failure are the most common problems, and all are repairable without replacing the entire engine in most cases. Whether you need a preventative water pump replacement or a full rebuilt engine with upgraded components and a 12-month warranty, EnginesMarket connects you with vetted UK specialists who know the N55 inside out. Compare prices today and keep your BMW on the road.
Compare rebuilt N55B30O0 BMW 1 Series M135i engine prices
12-Month Minimum
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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 1 Series M135i. Every engine supplied through EnginesMarket carries a minimum 12-month unlimited mileage warranty - always confirm exact terms with your chosen supplier."
BMW 1 Series M135i Engine ReplacementFrequently Asked Questions
Question 1How much does a BMW 1 Series M135i engine replacement cost-
A BMW 1 Series M135i engine replacement typically costs £3,500-£8,000 for a reconditioned or rebuilt N55 unit supply-only. With supply and fit, expect £5,000-£10,000 depending on the specialist and location. Main dealer new engine quotes can exceed £12,000 for parts alone.
- Used N55 engines: £1,800-£2,800
- Reconditioned N55: £3,500-£5,500
- Rebuilt N55 with warranty: £4,500-£8,000
Question 2What engine is in the BMW M135i-
The BMW M135i (F20/F21, 2012-2016) is powered by a 3.0-litre turbocharged straight-six petrol engine with the engine code N55B30. It produces 320 hp (235 kW) at 5,800 rpm and 450 Nm of torque from 1,300-4,500 rpm. The N55 features a single twin-scroll turbocharger, Valvetronic variable valve lift and direct injection.
- Engine Code: N55B30O0 / N55B30A
- Displacement: 2,979 cc
- Power: 320 hp
- Torque: 450 Nm
Question 3Is the BMW M135i engine reliable-
Yes - the N55 engine in the BMW M135i is generally regarded as reliable, with far fewer major failure points than the twin-turbo N54 it replaced. Common issues include oil leaks (valve cover gasket, oil filter housing gasket), Valvetronic wear, and water pump failure. Timing chain failure is incredibly rare on the N55, unlike the N47 and N20.
- N55 is more reliable than the N54
- No widespread timing chain issues
- Regular maintenance is essential for longevity
Question 4How long does a BMW 1 Series M135i engine replacement take-
A BMW 1 Series M135i engine replacement typically takes 2-4 days for a specialist to complete, including removal of the old N55 unit and fitting the replacement. The complexity of the six-cylinder turbo engine means labour time is higher than for four-cylinder models.
- Supply-only: engine delivered next working day in many cases
- Supply and fit: allow 2-4 working days
- Mobile fitting options limited due to engine complexity
Question 5What's the difference between the BMW M135i and M140i-
Both the BMW M135i and M140i are performance models of the 1 Series, but they use different engines. The M135i (2012-2016) uses the N55 3.0-litre turbocharged straight-six producing 320 hp, while the M140i (2016-2019) uses the B58 3.0-litre turbocharged straight-six producing 340 hp.
- M135i: 320 hp, N55 engine
- M140i: 340 hp, B58 engine (more reliable, more powerful)
Question 6Does a BMW 1 Series M135i rebuilt engine come with a warranty-
Yes - every rebuilt BMW 1 Series M135i engine supplied through EnginesMarket comes with a minimum 12-month unlimited-mileage warranty. This covers the engine against manufacturing defects and component failure, giving you peace of mind when investing in a replacement N55 unit.
- 12-month warranty is standard on all rebuilt engines
- Some specialists offer extended warranty options
- Always confirm exact warranty terms with your chosen supplier
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