Engines Market

BMW M135i SPECIALISTS

BMW 1 Series M135i Engine Replacement Compare 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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BMW 1 Series M135i Engine
from£3,500 to £8,000...
  • Usedfrom £1,800
  • Reconditionedfrom £3,500
  • Common codesN55B30A, N55B30O0
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How it works

3 Simple Steps to Finding the Right Replacement Engine

Clear information first, then the right engine and specialist for your exact vehicle.

Variant History

BMW 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
  1. 2012

    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

  2. 2013

    8-speed automatic transmission option introduced alongside the manual

  3. 2015

    F20/F21 LCI (Life Cycle Impulse) update; M135i continues with N55 engine producing 320 hp

  4. 2016

    M135i replaced by M140i with B58 engine producing 340 hp; the M135i badge is retired

Every engine fitted to the BMW 1 Series M135i is covered below, with UK rebuilt pricing and known failure points.

Engine Codes & Pricing

BMW 1 Series M135i Engine Codes Specifications & Replacement Cost

Find your exact engine code, specs and UK replacement cost guide.

N55B30O0 — 3.0L Turbocharged Petrol (2012-2016) engine

N55B30O0 — 3.0L Turbocharged Petrol (2012-2016)

Power Output
320 hp (235 kW) @ 5,800 rpm
Torque
450 Nm @ 1,300-4,500 rpm
Displacement
2,979 cc
Bore x Stroke
84 mm x 89.6 mm
Compression Ratio
10.2:1
Years Fitted
2012-2016

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Common Problems

BMW 1 Series M135i Engine Problems Repair Cost vs Replacement

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.

Common failure points and repair options

Oil Leaks

Affected
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.

Repair options

Repair tierDealer priceSpecialist price
Valve Cover Gasket Replacement£700-£1,000£400-£650
Oil Filter Housing Gasket Replacement£600-£900£350-£550
VANOS Solenoid Seal Replacement£500-£800£300-£500
Full Replacement - rebuilt engine£6,000-£9,000£4,500-£8,000
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.
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Valvetronic Motor & Eccentric Shaft Wear

Affected
BMW 1 Series M135i (N55B30, 2012-2016)
Typical failure mileage
60,000-120,000 miles
Root cause
The N55's Valvetronic system uses a motor with a worm gear that drives the eccentric shaft. The gears can become damaged due to insufficient lubrication from extended oil change intervals or restricted oil flow. If the motor worm gear becomes damaged, the likelihood that the gears on the eccentric shaft are damaged increases. In severe cases, the eccentric shaft can wear into the cylinder head.

Repair options

Repair tierDealer priceSpecialist price
Valvetronic Motor Replacement£700-£1,100£450-£750
Eccentric Shaft Replacement£1,800-£2,800£1,200-£2,000
Full Replacement - rebuilt engine£6,000-£9,000£4,500-£8,000
Our recommendation
Valvetronic issues are usually repairable without engine replacement. A diagnostic scan will identify if fault codes are present. If Valvetronic motor failure is detected, have the eccentric shaft inspected - catching wear early can prevent a much more expensive repair. Regular oil changes with BMW-approved oil are essential to prevent Valvetronic wear.
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Electric Water Pump & Charge Pipe Failure

Affected
BMW 1 Series M135i (N55B30, 2012-2016)
Typical failure mileage
50,000-100,000 miles
Root cause
The N55 uses an electric water pump that can fail without warning. Unlike belt-driven pumps, an electric pump failure may not be preceded by a visible leak. If the pump fails, the engine can overheat rapidly. The charge pipe, which connects the intercooler to the throttle body, is known to crack under boost pressure - particularly on tuned examples.

Repair options

Repair tierDealer priceSpecialist price
Water Pump & Thermostat Replacement£800-£1,200£500-£800
Charge Pipe Replacement£500-£800£300-£500
Full Replacement - rebuilt engine£6,000-£9,000£4,500-£8,000
Our recommendation
Water pump and thermostat replacement is recommended as preventative maintenance around 80,000-100,000 miles. If your M135i has not had the water pump replaced, consider doing so proactively. For the charge pipe, upgrading to an aluminium aftermarket unit is a popular and cost-effective solution that prevents future failure - especially if you're running increased boost.
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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.

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FAQ

BMW 1 Series M135i Engine ReplacementFrequently Asked Questions

Everything BMW 1 Series M135i owners usually ask before choosing a rebuilt, reconditioned or used replacement engine.

Why Choose Us

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