BMW 120d (F20) engine: which one, problems and replacement

The BMW 120d in the second 1 Series five-door generation (F20, built 2011–2019) was built with 2 different engines over its life: the N47D20 (184 hp, 2007–2016) and the N47D20D (184 hp, 2007–2015).

Below you will find how to identify the engine in your 120d, the faults to look for, current prices for a replacement and the swap options that make sense.

• Generation: second 1 Series five-door, 2011–2019
• Body styles: F20 (hatchback)
• Engines: N47D20, N47D20D
• Output: 184 hp
• Replacement engines in stock: 65 from 729,00 €

Which engine is in your 120d?

N47D20 in the 120d

The N47D20 was used in the F20 120d, built 2007–2016. It is a 2.0 L turbocharged diesel inline-4 with 184 hp and 380 Nm. It has the same output as the N47D20D, so the build date decides which one your car has.

Reading the code: N marks an N-series code, the generation of BMW engines introduced from 2001; 47 is the family number; D stands for diesel; 20 is the capacity in decilitres, so 2.0 litres.

N47D20D in the 120d

The N47D20D was used in the F20 120d, built 2007–2015. It is a 2.0 L turbocharged diesel inline-4 with 184 hp and 380 Nm. It has the same output as the N47D20, so the build date decides which one your car has.

Reading the code: N marks an N-series code, the generation of BMW engines introduced from 2001; 47 is the family number; D stands for diesel; 20 is the capacity in decilitres, so 2.0 litres; D identifies the version or output stage.

120d engines by model year

The engine changed once during the F20 run, in 2016. Changes usually come with BMW's mid-life update (LCI) or a new emissions standard, so a car registered early in a year can still have the older engine. The VIN settles it.

Other cars with the same engine as the 120d

A replacement engine does not have to come from another 120d. These models left the factory with the same engine code, so a unit from any of them is a candidate donor once the sump, mounts and ancillaries are matched to your car.

N47D20: BMW E90 320d, BMW F30 320d, BMW E84 X1 20d, BMW F25 X3 20d, BMW E60 520d.

N47D20D: BMW E90 320d, BMW F30 320d.

How to confirm your engine code

Because the 120d used more than one engine, the badge alone does not tell you which one your car has. The build date is the first clue; the VIN is the proof. Send us the last seven characters of the VIN and we read the engine code from BMW's records, or look for the code stamped on the block. How to find your BMW engine code.

Known 120d engine problems

The N47D20 and N47D20D in the 120d share the known weak points of the N47 family. Full N47 guide.

Timing chain. The timing chain stretches and in the worst case breaks, causing major engine damage. Engines built before 2011 are most affected.

Swirl flaps. Swirl flaps can stick or break.

EGR cooler. The EGR cooler can leak coolant; BMW issued a recall for some cars.

Diesel particulate filter. The DPF clogs on short-trip cars.

Injectors. Injectors leak or fail.

Symptoms to watch for on the 120d

Rattle for a few seconds after a cold start. The classic sign of a weak timing chain tensioner or stretched chain. It must be checked quickly: a chain that jumps a tooth can bend valves.

Rattle or whine from the gearbox end. On engines with the timing chain at the rear, a rattle or whine from the back of the engine is the warning sign of chain stretch or guide wear.

Whistle, loss of boost or limp mode. A split charge pipe, a sticking wastegate or worn turbo bearings. Check the pipes first, then the turbo shaft for play.

Black smoke under acceleration. Too much fuel for the air available: boost leaks, a sticking EGR valve, a dirty air mass meter or a leaking injector.

Hard starting when cold. Glow plugs or the glow plug control unit. On older diesels, also check the injection pump and fuel lines for air leaks.

Particulate filter warning. Short trips stop the DPF from regenerating. A long motorway run often clears it; a filter that keeps blocking may be covering an injector, EGR or turbo problem.

Sudden metallic noise followed by misfire. On diesels with swirl flaps, a broken flap or screw can enter a cylinder. Stop the engine immediately; continued running usually destroys the piston and head.

Looking after the 120d engine

• Oil: 5W-30 BMW Longlife-04, about 5.25 litres.
• Service interval: Oil every 10,000 to 15,000 km.
• Timing drive: Timing chain at the rear (gearbox end).
• Workshop notes: Replace the timing chain and guides when fitting a used N47 unless they were recently done.

Buying a used engine for the 120d: checklist

1. Confirm the exact engine code. Read the code stamped on the block and compare it with the code for your car. Send us the last seven characters of the VIN and we confirm the match before anything is paid.
2. List of what is fitted. Engines are sold with different ancillaries: some have the turbo, injectors, manifolds, alternator and starter, others are long blocks. Agree the list in writing so you know which parts must come from your old engine.
3. Sump, oil pickup and drive variants. Rear-drive, xDrive and front-drive cars can use different sumps, oil pickups and engine mounts even with the same engine code. Check that the sump matches your subframe and front axle.
4. Gearbox and flywheel match. Manual and automatic engines differ at the flywheel or flexplate, and sometimes at the crankshaft spigot. Make sure the engine you buy matches your gearbox or that you transfer the right parts.
5. Warranty terms in writing. Read what the warranty covers, how long it runs and what fitting conditions apply. Most warranties require a qualified workshop, new fluids and filters, and replacement of the cooling parts that caused the original failure.
6. Turbocharger shaft play and oil. Rotate the compressor wheel by hand. A small amount of side play is normal; in-and-out play or wheel contact with the housing is not. Oil pooled in the intake or intercooler pipes points to worn seals.
7. Injector correction values. On a diesel that can be run before removal, the injector correction values show whether one injector is delivering more or less fuel than the others. Large deviations mean an injector is on its way out.
8. Particulate filter and EGR history. Short-trip diesels clog their DPF and EGR systems. The engine may be fine, but ask whether the donor car had DPF warnings, and plan to clean or check your own filter before fitting.
9. Swirl flaps. Check whether the swirl flaps are in place, blanked or removed. Broken swirl flaps are a known cause of engine failure on several BMW diesels, so many owners fit blanking plates when the intake is off.
10. Timing chain noise. Listen for a rattle at the front of the engine for the first seconds after a cold start. On an engine that cannot be run, look at the chain guides through the oil filler or with the valve cover off.
11. Gearbox-end timing chain. On this engine the timing chain sits at the gearbox end, so replacing it normally means removing the engine. If the chain has not been replaced, the time to do it is before the engine goes into your car.

BMW 120d replacement engine cost

Our 120d engine stock runs to 65 units, priced from 729,00 € to 4.131,00 € with a median of 2.383,00 €.

Prices depend on the exact version, the donor's mileage, how complete the engine is and the demand for that code. Higher-output versions, low mileage and dressed engines with turbo, injectors and ancillaries cost more; long blocks and higher mileage cost less.

120d engine prices by model year

Engines from 2000–2004 have a median of 3.473,00 €, while units from 2020–2024 sit at 1.639,00 €. Newer engines usually cost more because they come from younger donor cars with lower mileage and later updates.

120d engine prices by mileage

Mileage matters less than history on a well-maintained BMW engine, but it is a useful guide. A low-mileage unit from a younger car gives you more life for a modest premium.

12 of these come from F20 donor cars, priced from 1.148,00 € to 3.299,00 €. An engine from the same body is the most direct swap because the sump, mounts and ancillaries already match.

On top of the engine, budget for the workshop's labour and the parts that are best replaced while the engine is out: engine mounts, the rear main seal, cooling parts, a clutch or converter seal, fluids and filters.

Replacement engines in stock for the 120d

Here is a selection of 120d engines currently on our shelves, photographed in the yard. Click any of them for the full photographs, mileage and specification.

BMW 125d F20 N47D20D Engine 20142.377,00 €BMW 125d F20 N47D20D Engine 2014 · 78000mi1.606,00 €Buy BMW 125d F20 N47D20D Engine 20121.951,00 €Used BMW 125d N47D20D 2011 Engine F203.299,00 €BMW F20 120d N47D20D Complete Engine1.354,00 €BMW 125d F20 N47D20D Engine 2019 · 85,000 km3.072,00 €BMW 125d F20 N47D20D Engine 2012 · 231,000 km3.241,00 €BMW 125d F20 N47D20D Engine 2016 · 57100mi2.614,00 €N47D20D Complete Engine BMW 125d F20 · 176,000 km2.710,00 €

BMW 125d F20 N47D20D Engine 2014 — 2.377,00 €, reduced from 3.000,00 €. It comes from a 2014 donor car, and 5 units are available. Ask the desk for compression figures or extra photographs before you order.

BMW 125d F20 N47D20D Engine 2014 · 78000mi — 1.606,00 €, reduced from 2.400,00 €. It comes from a 2014 donor car, and 24 units are available. We can confirm fitment against your VIN the same day.

Buy BMW 125d F20 N47D20D Engine 2012 — 1.951,00 €, reduced from 2.450,00 €. It comes from a 2012 donor car, and 10 units are available. Ask the desk for compression figures or extra photographs before you order.

Used BMW 125d N47D20D 2011 Engine F20 — 3.299,00 €, reduced from 4.250,00 €. It comes from a 2011 donor car, and 28 units are available. Ask the desk for compression figures or extra photographs before you order.

BMW F20 120d N47D20D Complete Engine — 1.354,00 €, reduced from 1.900,00 €. It comes from a recorded donor car, and 29 units are available. We can confirm fitment against your VIN the same day.

BMW 125d F20 N47D20D Engine 2019 · 85,000 km — 3.072,00 €, reduced from 3.600,00 €. It comes from a 2019 donor car with 85,000 km, and 14 units are available. The listing shows every side of the engine and the fitted parts.

BMW 125d F20 N47D20D Engine 2012 · 231,000 km — 3.241,00 €, reduced from 4.100,00 €. It comes from a 2012 donor car with 231,000 km, and 6 units are available. We can confirm fitment against your VIN the same day.

BMW 125d F20 N47D20D Engine 2016 · 57100mi — 2.614,00 €, reduced from 3.150,00 €. It comes from a 2016 donor car, and 22 units are available. The listing shows every side of the engine and the fitted parts.

N47D20D Complete Engine BMW 125d F20 · 176,000 km — 2.710,00 €, reduced from 3.200,00 €. It comes from a recorded donor car with 176,000 km, and 8 units are available. Ask the desk for compression figures or extra photographs before you order.

Will it fit my 120d?

Will the N47D20 fit my BMW F20 120d?

Yes, the BMW F20 120d left the factory with the N47D20, so an N47D20 from another car is the direct replacement. The second 1 Series five-door was built 2011–2019, and the N47D20 was produced 2007–2016, so check that your car's build date falls inside that window. Confirm the drive type (rear-drive or xDrive), the gearbox (manual or automatic) and the emissions standard, because these can change the sump, the flywheel and the software. Send us the VIN and we check all of it for you.

How much is a replacement engine for a BMW F20 120d?

We have 12 N47D20 engines from F20 donor cars, priced from 1.148,00 € to 3.299,00 €. Delivery to your door is included, and the engine carries a 12-month warranty when fitted by a qualified workshop. Add fitting labour and the parts you replace at the same time — seals, cooling parts and mounts — to estimate the total.

Will the N47D20D fit my BMW F20 120d?

Yes, the BMW F20 120d left the factory with the N47D20D, so an N47D20D from another car is the direct replacement. The second 1 Series five-door was built 2011–2019, and the N47D20D was produced 2007–2015, so check that your car's build date falls inside that window. Confirm the drive type (rear-drive or xDrive), the gearbox (manual or automatic) and the emissions standard, because these can change the sump, the flywheel and the software. Send us the VIN and we check all of it for you.

How much is a replacement engine for a BMW F20 120d?

We have 12 N47D20D engines from F20 donor cars, priced from 1.148,00 € to 3.299,00 €. Delivery to your door is included, and the engine carries a 12-month warranty when fitted by a qualified workshop. Add fitting labour and the parts you replace at the same time — seals, cooling parts and mounts — to estimate the total.

Engine swaps and upgrades for the 120d

These engines were fitted to other versions of the F20 at the factory, which makes them the most practical upgrades: the body was designed around them and many parts are shared.

Can I fit the N47D20T1 in my 120d?

Yes, it is one of the more common upgrades. Both are diesel inline-4 engines, so the mounting points are similar, but the N47D20T1 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 34 hp and 70 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Can I fit the N55B30 in my 120d?

It is a full conversion: the N55B30 runs on petrol and the N47D20D on diesel, so the fuel system, wiring, engine control unit, instrument coding and usually the gearbox change too. The gain is 122 hp and 20 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Fitting a replacement engine in the 120d

1. Inspect or replace the timing chain parts. Look at the guides and tensioner. On high-mileage engines, replacing them now costs far less than doing it later.
2. Replace the rear timing chain if in doubt. On engines with the chain at the gearbox end, chain work needs the engine out. If the history is unknown, replace the chain, guides and tensioner before fitting.
3. Prepare the turbo. Fit new oil feed and return seals, clean the intercooler and pipes of any oil or debris from the old engine, and prime the turbo with oil before starting.
4. Code the injectors and bleed the fuel. Enter the injector correction codes into the ECU, check the glow plugs and bleed the fuel system so the engine does not crank dry.
5. Check the particulate filter. If the old engine failed with oil or coolant entering the exhaust, the DPF may be contaminated. Check its back-pressure before relying on it.
6. Fill with the right oil and prime it. Fill with new oil of the correct specification and a new filter. Crank with the fuel and ignition disabled until oil pressure builds.
7. Coding and adaptations. On modern BMWs, the engine ECU must be matched to the car's immobiliser (CAS, FEM or BDC). Reset adaptations, register the battery and clear faults with diagnostic software.
8. First start and leak check. Start the engine, let it idle and watch oil pressure, temperature and fault codes. Check for leaks and bleed the cooling system.
9. First 1,000 km. Drive gently for the first few hundred kilometres, vary the engine speed and avoid full load. Change the oil and filter after about 1,000 km to remove any assembly debris.

The full fitting and first-start procedure.

Delivery, warranty and payment

Every 120d engine we sell is drained, sealed at each opening, strapped to a heat-treated pallet and shrink-wrapped before it leaves Hamburg. You receive photographs of the packed engine and a tracking number.

Door-to-door delivery is included to the address you give at checkout. Typical delivery takes three to five working days within Germany and neighbouring countries and five to ten working days to the rest of Europe and the UK.

A 12-month warranty covers eligible internal failure when the engine is fitted by a qualified workshop with new fluids and filters. You can pay by card, bank transfer or crypto and receive the invoice by email straight away.

All F20 engines · N47 engine guide · BMW 120d engines for sale · Send us your VIN