BMW 325i (E90) engine: which one, problems and replacement

The BMW 325i in the fifth 3 Series saloon generation (E90, built 2005–2012) was built with one engine, the N52B25: a 2.5 L petrol inline-6 with 218 hp.

Below you will find how to identify the engine in your 325i, the faults to look for, current prices for a replacement and the swap options that make sense.

• Generation: fifth 3 Series saloon, 2005–2012
• Body styles: E90 (saloon)
• Engines: N52B25
• Output: 218 hp
• Replacement engines in stock: 128 from 1.421,00 €

Which engine is in your 325i?

N52B25 in the 325i

The N52B25 was used in the E90 325i, built 2004–2011. It is a 2.5 L naturally aspirated petrol inline-6 with 218 hp and 250 Nm.

Reading the code: N marks an N-series code, the generation of BMW engines introduced from 2001; 52 is the family number; B stands for petrol (from the German Benzin); 25 is the capacity in decilitres, so 2.5 litres.

325i engines by model year

The 325i kept the same engine for the whole E90 run, which makes ordering simple: any unit with the same code fits, subject to the gearbox, drive type and sump.

Other cars with the same engine as the 325i

A replacement engine does not have to come from another 325i. 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.

N52B25: BMW E60 525i, BMW E85 Z4 2.5si, BMW E83 X3 2.5si.

How to confirm your engine code

The 325i only used the N52B25, but the exact version can still change with the build date, gearbox and market. 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 325i engine problems

The N52B25 in the 325i shares the known weak points of the N52 family. Full N52 guide.

Hydraulic lifter tick. Some engines tick on cold start because lifters drain down.

Electric water pump and thermostat. The pump fails around 100,000 km with little warning.

Valve cover gasket and eccentric shaft sensor. The plastic valve cover leaks and its sensor gasket fails.

Oil filter housing gasket. Leaks oil down the block and onto belts.

VANOS solenoids. Dirty solenoids cause rough idle and codes.

Symptoms to watch for on the 325i

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.

Poor low-down torque and uneven idle. VANOS seals or solenoids. The engine may run well at high revs but feel flat and lumpy at low speed.

Limp mode with a Valvetronic fault. The Valvetronic motor, its eccentric shaft sensor or the wiring. The engine runs on a reduced throttle until it is repaired.

Looking after the 325i engine

• Oil: 5W-30 BMW Longlife-01 or 04, about 6.5 litres.
• Service interval: Oil every 10,000 to 15,000 km.
• Timing drive: Timing chain at the front.
• Workshop notes: Fit a new water pump and thermostat with any used N52; they are on the outside and cheap compared with labour later.

Buying a used engine for the 325i: checklist

1. 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.
2. Look at the oil and coolant. Clean oil without metal particles and coolant without oil are good signs. Milky oil, oily coolant or a burnt smell mean the engine needs further checks before it is fitted.
3. 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.
4. 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.
5. Ask how the donor car was damaged. Most good used engines come from cars with body damage. A front-end impact can crack sensors, the timing cover or the sump; a rear or side impact usually leaves the engine untouched. The yard records the damage on each unit.
6. 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.
7. VANOS operation. Rough idle, a rattle from the front of the head and a loss of torque at low revs point to VANOS seals or solenoids. These are serviceable parts and are easier to renew with the engine out.
8. Double VANOS units and solenoids. Ask for the adaptation values or fault history if the engine was running. Solenoids are inexpensive and are often replaced as a matter of course on a used engine.
9. Valvetronic motor and eccentric shaft sensor. The Valvetronic motor and its sensor cause limp-mode faults when they fail. Inspect the connector and the seal around the motor for oil.
10. Electric water pump. This engine uses an electric water pump. It fails without warning and needs a diagnostic bleeding routine when it is replaced or the system is refilled.

BMW 325i replacement engine cost

We currently hold 128 325i engine engines. The cheapest is 1.421,00 €, the most expensive 2.300,00 €, and half of them cost less than 1.841,00 €.

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.

325i engine prices by model year

Engines from 2005–2009 have a median of 1.801,00 €, while units from 2010–2014 sit at 1.890,00 €. Newer engines usually cost more because they come from younger donor cars with lower mileage and later updates.

325i 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.

43 of these come from E90 donor cars, priced from 1.423,00 € to 2.255,00 €. 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 325i

Here is a selection of 325i engines currently on our shelves, photographed in the yard. Click any of them for the full photographs, mileage and specification.

BMW E90 325i N52B25 Engine 2011, 206,400 km1.538,00 €BMW E90 325i N52B25 Engine 2005, 61,500 km1.461,00 €BMW E90 325i N52B25 Engine 2007, 187,500 km1.579,00 €BMW E90 325i N52B25 Engine 2008, 18,000 km1.651,00 €BMW E90 325i N52B25 Engine 2011, 125,800 km2.189,00 €BMW E90 325i N52B25 Engine 2010, 149,000 km1.507,00 €BMW E90 325i N52B25 Engine 2010, 113,200 km2.181,00 €BMW E90 325i N52B25 Engine 2011, 102,200 km2.179,00 €BMW E90 325i N52B25 Engine 2010, 77,900 km2.042,00 €BMW E90 325i N52B25 Engine 2010, 181,900 km2.116,00 €BMW E90 325i N52B25 Engine 2007, 196,900 km1.627,00 €BMW E90 325i N52B25 Engine 2005, 164,700 km2.139,00 €

BMW E90 325i N52B25 Engine 2011, 206,400 km — 1.538,00 €, reduced from 2.300,00 €. It comes from a 2011 donor car with 206,400 km, and 5 units are available. We can confirm fitment against your VIN the same day.

BMW E90 325i N52B25 Engine 2005, 61,500 km — 1.461,00 €, reduced from 2.800,00 €. It comes from a 2005 donor car with 61,500 km, and 6 units are available. The listing shows every side of the engine and the fitted parts.

BMW E90 325i N52B25 Engine 2007, 187,500 km — 1.579,00 €, reduced from 2.800,00 €. It comes from a 2007 donor car with 187,500 km, and 14 units are available. The listing shows every side of the engine and the fitted parts.

BMW E90 325i N52B25 Engine 2008, 18,000 km — 1.651,00 €, reduced from 2.550,00 €. It comes from a 2008 donor car with 18,000 km, and 21 units are available. Ask the desk for compression figures or extra photographs before you order.

BMW E90 325i N52B25 Engine 2011, 125,800 km — 2.189,00 €, reduced from 3.050,00 €. It comes from a 2011 donor car with 125,800 km, and 11 units are available. We can confirm fitment against your VIN the same day.

BMW E90 325i N52B25 Engine 2010, 149,000 km — 1.507,00 €, reduced from 2.600,00 €. It comes from a 2010 donor car with 149,000 km, and 5 units are available. The listing shows every side of the engine and the fitted parts.

BMW E90 325i N52B25 Engine 2010, 113,200 km — 2.181,00 €, reduced from 3.500,00 €. It comes from a 2010 donor car with 113,200 km, and 14 units are available. The listing shows every side of the engine and the fitted parts.

BMW E90 325i N52B25 Engine 2011, 102,200 km — 2.179,00 €, reduced from 3.250,00 €. It comes from a 2011 donor car with 102,200 km, and 9 units are available. We can confirm fitment against your VIN the same day.

BMW E90 325i N52B25 Engine 2010, 77,900 km — 2.042,00 €, reduced from 2.700,00 €. It comes from a 2010 donor car with 77,900 km, and 29 units are available. Ask the desk for compression figures or extra photographs before you order.

BMW E90 325i N52B25 Engine 2010, 181,900 km — 2.116,00 €, reduced from 3.350,00 €. It comes from a 2010 donor car with 181,900 km, and 13 units are available. Ask the desk for compression figures or extra photographs before you order.

BMW E90 325i N52B25 Engine 2007, 196,900 km — 1.627,00 €, reduced from 2.550,00 €. It comes from a 2007 donor car with 196,900 km, and 27 units are available. The listing shows every side of the engine and the fitted parts.

BMW E90 325i N52B25 Engine 2005, 164,700 km — 2.139,00 €, reduced from 3.100,00 €. It comes from a 2005 donor car with 164,700 km, and 17 units are available. We can confirm fitment against your VIN the same day.

Will it fit my 325i?

Engine swaps and upgrades for the 325i

These engines were fitted to other versions of the E90 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 N51B30 in my 325i?

Yes, it is one of the more common upgrades. Both are petrol inline-6 engines, so the mounting points are similar, but the N51B30 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 12 hp and 20 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Can I fit the N52B30 in my 325i?

Yes, it is one of the more common upgrades. Both are petrol inline-6 engines, so the mounting points are similar, but the N52B30 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 40 hp and 50 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Can I fit the N53B30 in my 325i?

Yes, it is one of the more common upgrades. Both are petrol inline-6 engines, so the mounting points are similar, but the N53B30 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 54 hp and 70 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Fitting a replacement engine in the 325i

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. Reset VANOS adaptations. Clear the VANOS adaptations so the ECU learns the camshaft positions of the new engine.
3. Teach the Valvetronic limit stops. Run the Valvetronic learning routine so the ECU knows the eccentric shaft limits.
4. 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.
5. 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.
6. 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.
7. 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.

325i engine questions

How much is a replacement N52B25 engine for a BMW E90 325i?

A used N52B25 for the BMW E90 325i costs from about 1.400 € to 2.350 € in our yard. The price depends on the year, the mileage and the parts that come with the engine.

Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Inside the EU there is no import duty. Outside the EU, the receiver pays local duty and VAT.

A replacement engine is often much cheaper than rebuilding a damaged one, and much faster. The N52B25 you buy is photographed and checked in Hamburg before it is listed.

Eligible engines come with a 12 months warranty from the delivery date. It covers internal mechanical failure under normal use and correct fitting by a qualified mechanic or workshop. Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.

See all N52 Engines · Search N52B25 in the shop

Will the N52B25 engine fit my BMW E91 325i?

Yes, if your BMW E91 325i was built with the N52B25. BMW used this 2.5 liter (2,497 cc) petrol engine with 160 kW (218 HP) in the E91 325i from about 2005 to 2011.

In our records the N52B25 is the engine for the E91 325i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E91 has a manual or an automatic gearbox. The flywheel or the flex plate and some sensors depend on it.

Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.

See all N52 Engines · Search N52B25 in the shop

Will the N52B25 engine fit my BMW E90 325i?

Yes, if your BMW E90 325i was built with the N52B25. BMW used this 2.5 liter (2,497 cc) petrol engine with 160 kW (218 HP) in the E90 325i from about 2005 to 2011.

In our records the N52B25 is the engine for the E90 325i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E90 has a manual or an automatic gearbox. The flywheel or the flex plate and some sensors depend on it.

Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.

See all N52 Engines · Search N52B25 in the shop

What comes with a used N52B25 engine?

Each N52B25 is sold as described on its own listing. The yard writes down the parts that are fitted to that unit, such as the turbo, the injectors, the manifolds or the alternator, so you know what arrives.

Some units are long engines with few ancillaries, others are more complete. If you need a part that is not listed, ask the desk. We often have the matching items in the yard.

Every engine is drained, sealed at each opening, strapped to a heat-treated pallet and shrink-wrapped, then photographed before it leaves the yard.

On delivery, the carrier brings the pallet to the kerb or a loading bay. Please have a forklift, a pallet truck or an engine crane ready.

See all N52 Engines · Search N52B25 in the shop

What is the difference between the N52B25 and other N52 engines?

The N52B25 makes 160 kW (218 HP) and 250 Nm. The other N52 engines are: N52B30 with 190 kW (258 HP) and 310 Nm (2005 to 2011).

Engines in one family share a basic block, but the turbo, the injection, the sensors and the engine computer can differ. A higher power version often has different pistons, a bigger turbo or a different fuel system.

This is why we ask for the exact code. Fitting a different version can work, but the wiring, the software and sometimes the gearbox must be changed to match.

Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.

See all N52 Engines · Search N52B25 in the shop

How long does delivery of an N52B25 engine take?

Orders confirmed before 14:00 CET on a working day leave Hamburg the same day. Later and weekend orders leave the next working day. Delivery to the Netherlands, Belgium, Germany, France, Luxembourg and Denmark takes 1 to 3 working days.

Spain, Italy, Portugal, Poland, Czechia, Austria, Ireland, the Nordics and the Baltics take 2 to 5 working days. Greek and Spanish islands, Malta, Cyprus and remote areas take 4 to 8 working days. The UK and other countries outside the EU are quoted one by one.

Shipping is a flat 249 € per order. It is added once at checkout and printed on the invoice, so there is no extra fee later. Every engine is drained, sealed at each opening, strapped to a heat-treated pallet and shrink-wrapped, then photographed before it leaves the yard.

You get a tracking number when the pallet is collected. Check the wrapping before you sign, and note any damage on the paperwork.

See all N52 Engines · Search N52B25 in the shop

Does a used N52B25 engine come with a warranty?

Yes. Eligible engines come with a 12 months warranty from the delivery date. It covers internal mechanical failure under normal use and correct fitting by a qualified mechanic or workshop.

The warranty does not cover damage from wrong fitting, overheating, low oil, wrong fluids or fuel, engines that were opened or modified without our approval, or labour and towing costs.

To claim, send us your order number, a short description of the problem, photos or a video, and a mechanic's report if we ask for one. If the claim is approved, we repair, replace or refund the engine.

Keep the receipts for the fitting, the oil and the filters. They make any claim quick and simple.

See all N52 Engines · Search N52B25 in the shop

What should I replace when I fit a used N52B25 engine?

A used engine lasts longest when it starts life in your car with fresh fluids and new seals. Check the spark plugs and the ignition coils, and make sure the fuel lines are clean and tight before you crank the engine. Fit a new oil filter and fresh oil of the grade BMW lists for this engine, and refill the coolant with the correct BMW antifreeze mix. Use new gaskets for the exhaust manifold, the intake and the sump plug, and check every hose clip before the first start.

Look at the engine mounts and the clutch or the torque converter while the engine is out. Old mounts can crack a new engine's brackets, and a worn clutch is much easier to change now.

Before the first start, turn the engine over without fuel until the oil pressure light goes out. Then let it idle, check for leaks, and drive gently for the first few hundred kilometres.

The warranty asks for fitting by a qualified mechanic and the correct oil, coolant and filters. Keep your receipts in case you ever need to make a claim.

See all N52 Engines · Search N52B25 in the shop

Is the BMW N52B25 a diesel or petrol engine?

The N52B25 is a petrol engine. It is a 2.5 liter (2,497 cc) inline 6, DOHC, 24 valve unit with no turbo (naturally aspirated), and it was built to the Euro 4 emission standard.

The emission standard matters for registration and for low-emission zones in many cities. When you replace an engine with the same code, the car keeps the same paperwork and the same emission class.

Petrol versions need the correct catalytic converters and oxygen sensors on the car to stay legal and to keep the engine computer happy. Reuse the parts from your car if they are in good condition.

If you are not sure which version you need, send us your VIN. We tell you the right code for free.

See all N52 Engines · Search N52B25 in the shop

Will the N52B25 engine fit my BMW E91 325i?

Yes, if your BMW E91 325i was built with the N52B25. BMW used this 2.5 liter (2,497 cc) petrol engine with 160 kW (218 HP) in the E91 325i from about 2005 to 2011.

In our records the N52B25 is the engine for the E91 325i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E91 has a manual or an automatic gearbox. The flywheel or the flex plate and some sensors depend on it.

Not sure? Send us your VIN and your gearbox code. We match the engine family, the year window and the parts on the engine before anything is reserved, and the check is free.

See all N52 Engines · Search N52B25 in the shop

Delivery, warranty and payment

Before a 325i engine leaves our Hamburg yard it is drained of oil and coolant, every opening is sealed, and it is strapped to a pallet and wrapped. We send photographs of the packed unit and the tracking details.

Delivery is door to door and included in the price. Most European addresses receive the engine within five to ten working days; Germany and its neighbours are usually faster.

Every engine carries a 12-month warranty on eligible internal failure when a qualified workshop fits it with new fluids and filters. Payment is by card, bank transfer or crypto; your invoice is emailed as soon as you order.

All E90 engines · N52 engine guide · BMW 325i engines for sale · Send us your VIN