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Select your BMW 1 Series Model

BMW 1 Series Engines

Model Name Engine code Year Engine size Chassis Fuel KW HP Cylinders Valves
1 Series M 135i B48 A20 E 2019-2025 1998cc 1 Petrol 1951 2251 41 161
1 Series 125d N47 D20 D 2011-2016 2.0 F201 Diesel 1501 1601 41 161
1 Series 125d B47 D20 B 2011-2016 2.0 F201 Diesel 851 1701 41 161
1 Series 135I N55 B30 A 2007-2014 3.0 E821 Petrol 2001 2721 61 241
1 Series 135I N54 B30 A 2007-2014 3.0 E821 Petrol 2001 2641 61 241
1 Series 135I N52 B30 AF 2005-2012 3.0 E871 Petrol 1791 2001 61 241
1 Series 135I N52 B30 B 2005-2012 3.0 E871 Petrol 1601 2001 61 241
1 Series 135I N52 B30 BF 2005-2012 3.0 E871 Petrol 1601 2001 61 241
1 Series 135I N52 B30 A 2005-2012 3.0 E871 Petrol 1551 2001 61 241

Used and Reconditioned BMW 1 Series Replacement Engines Services for 125d, 135i and M 135i Across the UK

If your BMW 1 Series has suffered serious engine damage, BM Engine Works can help you choose a suitable repair, rebuild or replacement. We supply tested used BMW 1 Series engines and offer reconditioned or rebuilt solutions for selected BMW 125d, BMW 135i and BMW M135i applications, subject to the exact engine code, vehicle specification and availability.

With more than 30 years of engine experience, our team matches each option by registration or VIN, full engine code, production date, fuel type, gearbox, drivetrain and emissions specification. This helps prevent problems with mounts, wiring, ECU communication, ancillaries and coding after installation.

Choose supply only delivery if you already have a competent installer, or book in house supply and fitting at our Rainham workshop. Eligible engines and services are available with written warranty cover of up to 12 months. Depending on the engine and service selected, you may save up to 40% compared with the price of a brand new replacement engine.

BMW 1 Series Models and Engine Codes We Work With

Here are the engine codes for which BM Engine Works is recognised as a leading specialist in the UK. If your 1 Series model or engine code isn't listed below, don't worry; our certified technicians are equipped to provide top-notch service for all types of 1 Series engines throughout the UK. We typically complete all engine work within 5 to 10 working days, ensuring you spend minimal time off the road.

  • BMW M135i: B48 A20 E (2019-2025, 1998cc petrol).
  • BMW 125d: B47 D20 B and N47 D20 D (2011-2016, 2.0 diesel, F20).
  • BMW 135i: N55 B30 A, N54 B30 A, N52 B30 A, N52 B30 AF, N52 B30 B and N52 B30 BF (2007-2014 E82; 2005-2012 E87; 3.0 petrol).

Choose the Right BMW 1 Series Engine Solution

The lowest purchase price is not always the lowest total cost. The right option depends on the confirmed fault, condition of the original engine, vehicle value, budget, expected ownership period and the warranty offered.

Option When it may be suitable and what to confirm
Tested used engine A practical lower cost choice when a compatible donor engine is available. Confirm the exact engine code and suffix, mileage evidence where available, test results, included parts and warranty terms.
Reconditioned or rebuilt unit A suitable choice when the vehicle will be kept longer or the failed engine has major internal damage. Confirm the written build scope, measurements, machining, replaced parts, testing, assembly level and warranty.
Rebuild your original engine Suitable when the main castings are serviceable and keeping the vehicle's original engine is preferred. Confirm the strip down findings, machining limits, replacement parts, final testing and any costs that may change after inspection.
Targeted repair Suitable when the fault is isolated and has not caused wider internal damage. Confirm the root cause, affected parts, condition of the remaining engine and warranty for the completed repair.

Used BMW 1 Series Engines for Sale: Save Up to 40%

A used BMW 1 Series engine is an original unit removed from another vehicle. It can be a practical choice when you need a quicker, lower cost replacement for an older car or a repair budget must be controlled. Condition varies between engines, so the quoted unit should be judged on its own evidence rather than a general promise about every used engine.

Before confirming a unit, we check compatibility and review the information available for that engine. Ask for the recorded mileage or donor evidence where available, test information, visible condition, engine number, assembly level and written warranty. A bare engine, long engine and complete engine do not include the same components, so the quotation must state exactly what will be supplied.

Used BMW 1 Series engines are available for supply only or in house fitting, subject to stock. Nationwide delivery also available. So, you can get the quality BMW 1 Series engine (125d, 135i, M135i) to your desired location anywhere in the UK. For customer requests, we can also arrange BMW 1 Series worldwide delivery service with DHL/TNT. If we fit the engine, we can also inspect the vehicle systems that may have caused the original failure before commissioning the replacement.

Reconditioned and Rebuilt BMW 1 Series Engines

A reconditioned or rebuilt BMW 1 Series engine is dismantled so its internal condition can be assessed. The terms 'reconditioned', 'rebuilt' and 'remanufactured' are used differently across the engine trade, so the written work specification matters more than the label alone.

A proper build specification may include:

  • Complete dismantling and cleaning of the agreed engine assembly.
  • Inspection and measurement of the block, cylinder head, crankshaft, connecting rods and other reusable parts.
  • Pressure testing and machining where inspection shows it is required and technically suitable.
  • Replacement of damaged or worn components listed in the quotation, including bearings, seals, gaskets and timing parts where applicable.
  • Reassembly to the specified clearances and torque settings.
  • Oil system priming, leak checks, diagnostic checks and operational testing appropriate to the completed engine.
  • A written record of the agreed build scope, assembly level and warranty conditions.

If the original engine is rebuildable, an in house rebuild can retain that unit. If the damage is too severe or the castings are outside service limits, we can discuss a compatible replacement instead.

BMW 1 Series Engine Common Problems by Engine Code

The problem headings below name the engine codes to which each diagnostic area is relevant. These are possible fault areas, not a prediction that every listed engine will develop every problem. Similar symptoms can have different causes, so the exact engine code and test results must be confirmed before repair or replacement.

Problem heading and applicable engine code(s) Typical signs Diagnostic direction
Timing chain wear, rattle or valve timing fault
N47 D20 D; B47 D20 B		 Metallic cold start rattle, hard starting, timing or correlation faults, reduced power. Read fault memory; compare camshaft and crankshaft correlation; check oil pressure, tensioner, guides and chain condition.
EGR valve or EGR cooler fault
N47 D20 D; B47 D20 B		 Coolant loss, warning light, rough running, smoke or reduced power. Check the VIN for an open BMW recall or campaign, then test EGR operation, cooler integrity and the cooling system.
DPF loading or failed regeneration
N47 D20 D; B47 D20 B		 Frequent regeneration, DPF warning, limp mode, poor economy, fan operation or smoke. Check soot and ash values, differential pressure and temperature sensors, then diagnose injector, EGR or thermostat causes.
High pressure fuel pump or rail pressure fault
N54 B30 A; N55 B30 A; B48 A20 E		 Long cranking, non-start, hesitation, reduced power or fuel pressure fault codes. Compare commanded and actual rail pressure, verify the low-pressure supply and test for leakage before replacing parts.
Injector leakage, correction or electrical fault
N47 D20 D; B47 D20 B; N54 B30 A; N55 B30 A; B48 A20 E		 Rough idle, misfire, hard starting, fuel smell, smoke or rising oil level. Review correction and misfire data; perform leak off or leak down checks as appropriate; verify coding and injector specification.
Turbocharger, wastegate or boost control fault
N47 D20 D; B47 D20 B; N54 B30 A; N55 B30 A; B48 A20 E		 Underboost, limp mode, rattle, whistle, smoke or high oil use. Pressure or smoke test the intake; inspect hoses, actuator or wastegate operation, turbo condition and oil feed and return.
Electric coolant pump or thermostat fault
N52 B30 A; N52 B30 AF; N52 B30 B; N52 B30 BF; N54 B30 A; N55 B30 A		 Overheating, coolant warning, radiator fan at high speed or weak cabin heat. Read cooling faults, activate the pump where possible, verify coolant flow and pressure test the system before internal engine work.
Oil filter housing, valve cover or upper engine oil leak
N52 B30 A; N52 B30 AF; N52 B30 B; N52 B30 BF; N54 B30 A; N55 B30 A; B48 A20 E		 Burning oil smell, smoke, visible oil, belt contamination or falling oil level. Clean and trace the leak source; inspect the drive belt and pulleys; check the housing, cover, seals and crankcase pressure.
Crankcase ventilation (PCV) fault
N52 B30 A; N52 B30 AF; N52 B30 B; N52 B30 BF; N54 B30 A; N55 B30 A; B48 A20 E		 Whistling, excessive crankcase vacuum, oil use, smoke or rough idle. Measure crankcase vacuum, smoke test for intake leaks and inspect the breather diaphragm, valve cover and connected hoses.
Ignition coil or spark plug misfire
N52 B30 A; N52 B30 AF; N52 B30 B; N52 B30 BF; N54 B30 A; N55 B30 A; B48 A20 E		 Shaking, hesitation, flashing warning light, poor starting or reduced power. Review misfire counts and plugs condition; swap test coils; continue with injector and compression checks if the misfire remains.

Diagnostic note: Match the full engine code and VIN before quoting work. A listed association does not prove the cause, and a warning light or loss of power does not by itself mean that a complete engine is required.

Why Exact Engine Code Matching Matters

BMW can revise an engine within the same model badge and registration year. Differences may affect sensors, injectors, turbocharger, sump, mounts, wiring, ECU software, emissions equipment, gearbox connection and drivetrain. A similar looking engine is not necessarily a direct replacement.

BM Engine Works uses the following information before confirming an engine:

  • Vehicle registration and full VIN.
  • Model, chassis code and production date.
  • Complete engine code and suffix, not only the broad family name.
  • Petrol or diesel specification, output and emissions standard.
  • Manual or automatic gearbox and front, rear or All Wheel Drive configuration.
  • Required assembly level and the ancillaries that must transfer from the old engine.

Our BMW 1 Series Engine Replacement Process

  1. Send the vehicle details. Provide the registration or VIN, postcode, current symptoms and whether you need supply only or fitting.
  2. Confirm the fault. For workshop jobs, we diagnose the vehicle and check whether repair, rebuild or replacement is the sensible route.
  3. Match the correct engine. We confirm the code, suffix, production specification, gearbox, drivetrain and required assembly level.
  4. Approve an itemised quote. The quote sets out the engine type, labour, included parts, delivery or recovery, expected timescale and warranty.
  5. Fit or dispatch. Supply only engines are prepared for delivery. Fitting and rebuilding are completed in house at our Rainham workshop.
  6. Test and hand over. For fitted jobs, we prime and fill the systems, check for leaks, complete diagnostics and test the vehicle before collection.

BMW 1 Series Engine Supply, In House Fitting & Delivery Option

Supply only is suitable when you already have a competent installer. We can arrange UK wide engine delivery and provide the identification and warranty information that applies to the quoted unit.

BM Engine Works offers complete supply and fitting service for BMW 1 Series, which is completed in-house. Our team removes the failed unit, checks related systems, installs the replacement and carries out the agreed diagnostic and commissioning work. Vehicle recovery can also be arranged where available. We do not describe engine fitting as a mobile delivery service.

BMW 1 Series Engine Replacement Cost and Turnaround

There is no single BMW 1 Series engine replacement cost. The price depends on the exact engine code, used or reconditioned condition, donor evidence, rebuild damage, assembly level, included ancillaries, labour, coding, delivery or recovery and warranty. A clear quote should separate these items so that you can compare the true total rather than an incomplete engine only headline price.

Selected used and reconditioned options can save up to 40% compared with the price of a brand new engine. Most in house supply and fit jobs are planned around an estimated 5-10 working days once diagnosis, engine availability and the work scope are confirmed. Complex damage, machining, parts delays or additional faults can change the timescale, so the expected completion date is confirmed with the individual quotation.

BMW 1 Series Engine Warranty and Aftercare Support

Eligible BMW 1 Series engines and replacement services are available with written warranty cover of up to 12 months. The exact duration, mileage limit, covered components, labour position, exclusions and claim process depend on the unit and service selected. These terms should be read before payment.

A replacement engine still relies on healthy oil, cooling, intake, fuel, turbo and emissions systems. Any fault that caused the original failure must be corrected. Follow the specified oil and service requirements, keep all invoices, and respond immediately to oil pressure, coolant temperature or drivetrain warnings.

Why Choose BM Engine Works?

  • More than 30 years of practical engine experience.
  • BMW focused engine code matching, diagnostics and technical support.
  • Used, reconditioned, rebuilt and original engine rebuild options.
  • In house engine rebuilding, fitting, coding and commissioning.
  • Supply only engine delivery across the UK and vehicle recovery options.
  • Itemised quotations that explain the engine, labour, parts, timescale and warranty.
  • Warranty cover of up to 12 months on eligible engines and services, subject to written terms.
  • Potential savings of up to 40% against brand new engine pricing on selected options.

Get a Quote for Your BMW 1 Series Engine

Send us your registration number or VIN, model year, engine code if known, current fault, postcode and preferred service. We will check the compatible BMW 1 Series engine options and provide a quote for supply only, in house supply and fitting, or rebuilding your existing engine.

Frequently Asked Questions

The price depends on the engine code, condition, assembly level, included ancillaries and whether you need supply only or fitting.
A tested used engine can suit a controlled budget or an older car. A reconditioned or rebuilt engine may suit longer ownership or major damage.
Our listed range covers the BMW 125d with B47 D20 B or N47 D20 D, the BMW 135i with N55 B30 A, N54 B30 A, N52 B30 A, N52 B30 AF, N52 B30 B or N52 B30 BF, and the BMW M135i with B48 A20 E. Registration or VIN matching is required before a unit is confirmed.
Yes. We can arrange UK wide delivery, and the quote will state the assembly level, delivery terms, installation conditions and warranty.
Yes. Supply and fitting is completed in house at our Rainham workshop. The service can include diagnosis, removal, installation, fluids, coding, testing and handover according to the written quote.
Most in house supply and fit jobs are estimated at 5 to 10 working days after the fault, engine availability and work scope are confirmed. Machining, additional damage or parts delays can extend this time.
Eligible engines and services are available with warranty cover of up to 12 months. The exact time and mileage limit, parts and labour position, exclusions and claim procedure are confirmed in writing for the quoted option.
A bare, long and complete engine includes different components. The quote should list the turbo, injectors, pumps, alternator, starter, DPF, EGR, ECU, clutch, flywheel and other ancillaries as included, reused or charged separately.
Common enquiries include timing related noise, oil use, smoke, coolant loss, overheating, misfires, limp mode, low oil pressure and internal knocking. These symptoms need diagnosis because the cause may be an ancillary fault, a repairable engine problem or major internal damage.
No. Rebuilding or replacing an engine does not reset the vehicle's odometer. Keep the invoice, engine details and work records with the service history.
The old unit may be returned as an exchange core, retained for rebuild or handled as agreed in the quotation. Confirm ownership, collection and any core surcharge before approving the work.

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