BMW 325i (E46) engine: which one, problems and replacement

The BMW 325i in the fourth 3 Series generation (E46, built 1997–2006) was built with one engine, the M54B25: a 2.5 L petrol inline-6 with 192 hp.

This guide tells you which engine your 325i has, what goes wrong with it, what a replacement costs from our stock and what else to plan for when you fit one.

• Generation: fourth 3 Series, 1997–2006
• Body styles: E46 (saloon, Touring, coupé, convertible, Compact)
• Engines: M54B25
• Output: 192 hp
• Replacement engines in stock: 11 from 887,00 €

Which engine is in your 325i?

M54B25 in the 325i

The M54B25 was used in the E46 325i, built 2000–2006. It is a 2.5 L naturally aspirated petrol inline-6 with 192 hp and 245 Nm.

Reading the code: M marks an M-series code, the naming BMW used for its engine families up to the early 2000s; 54 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 E46 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.

M54B25: BMW E60 525i, BMW E39 525i, BMW E85 Z4 2.5, BMW E83 X3 2.5.

How to confirm your engine code

The 325i only used the M54B25, 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 M54B25 in the 325i shares the known weak points of the M54 family. Full M54 guide.

Crankcase ventilation (CCV). A failed CCV valve causes oil consumption, a whistle at idle, smoke and lean-running codes. It is the most common M54 fault.

DISA valve flap. The plastic flap inside the DISA valve can break and enter the engine.

Cooling system. Expansion tanks, thermostats and water pumps fail around 100,000 km.

Oil filter housing and valve cover gaskets. Both harden and leak oil onto the exhaust and alternator.

Oil consumption from piston rings. Some engines burn oil when rings stick, often after short-trip use.

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.

Looking after the 325i engine

• Oil: 5W-30 BMW Longlife-01 synthetic, about 6.5 litres with filter.
• Service interval: Oil every 15,000 km or yearly; spark plugs every 100,000 km; cooling every 100,000 km.
• Timing drive: Duplex and single chains at the front, no scheduled replacement.
• Workshop notes: Change the CCV system and DISA valve before fitting a used M54. Both are cheap compared with an engine.

Buying a used engine for the 325i: 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. Why your old engine failed. Before fitting a replacement, find out why the original failed. An overheating radiator, a blocked intercooler or a failed turbo can destroy a second engine if they are not fixed.
3. 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.
4. 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.
5. 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.
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. Plastic cooling parts. Expansion tanks, thermostat housings and water pump impellers made of plastic crack with age. Plan to replace them when the engine is fitted.

BMW 325i replacement engine cost

Our 325i engine stock runs to 11 units, priced from 887,00 € to 3.112,00 € with a median of 1.723,00 €.

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 2000–2004 have a median of 1.697,00 €, while units from 2005–2009 sit at 2.614,00 €. Newer engines usually cost more because they come from younger donor cars with lower mileage and later updates.

2 of these come from E46 donor cars, priced from 887,00 € to 3.112,00 €. 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

These 325i units are in our Hamburg yard right now. Each listing shows real photographs of the engine you receive, its mileage and what is fitted.

BMW E46 325i M54B25 Engine 2002887,00 €BMW E85 Z4 2.5 M54B25 Complete Engine1.732,00 €BMW M54B25 Engine1.795,00 €BMW E83 X3 2.5 M54B25 Complete Engine1.741,00 €BMW E39 525i M54B25 Complete Engine1.723,00 €

BMW E46 325i M54B25 Engine 2002 — 887,00 €, reduced from 1.200,00 €. It comes from a 2002 donor car, and 17 units are available. We can confirm fitment against your VIN the same day.

BMW E85 Z4 2.5 M54B25 Complete Engine — 1.732,00 €, reduced from 2.200,00 €. It comes from a recorded donor car, and 18 units are available. We can confirm fitment against your VIN the same day.

BMW M54B25 Engine — 1.795,00 €, reduced from 2.200,00 €. It comes from a recorded donor car, and 17 units are available. The listing shows every side of the engine and the fitted parts.

BMW E83 X3 2.5 M54B25 Complete Engine — 1.741,00 €, reduced from 2.200,00 €. It comes from a recorded donor car, and 13 units are available. Ask the desk for compression figures or extra photographs before you order.

BMW E39 525i M54B25 Complete Engine — 1.723,00 €, reduced from 2.200,00 €. It comes from a recorded donor car, and 16 units are available. The listing shows every side of the engine and the fitted parts.

Will it fit my 325i?

Engine swaps and upgrades for the 325i

These engines were fitted to other versions of the E46 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 M52TUB28 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 M52TUB28 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 1 hp and 35 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Can I fit the M57D30TU in my 325i?

It is a full conversion: the M57D30TU runs on diesel and the M54B25 on petrol, so the fuel system, wiring, engine control unit, instrument coding and usually the gearbox change too. The gain is 26 hp and 255 Nm. In Germany and most of Europe an engine swap must be inspected and registered.

Can I fit the M54B30 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 M54B30 needs its own wiring and engine control unit, the matching gearbox or clutch, and often a different sump, cooling and exhaust. The gain is 39 hp and 55 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. 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.
4. 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.
5. 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.
6. 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

Will the M54B25 engine fit my BMW E46 325i?

Yes, if your BMW E46 325i was built with the M54B25. BMW used this 2.5 liter (2,494 cc) petrol engine with 141 kW (192 HP) in the E46 325i from about 2000 to 2006.

In our records the M54B25 is the engine for the E46 325i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E46 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 M54 Engines · Search M54B25 in the shop

Does a used M54B25 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 M54 Engines · Search M54B25 in the shop

How do I know a used M54B25 engine is in good shape?

Before a unit is listed, the yard checks the engine code against the listing, writes down the parts fitted to it, seals every opening and photographs the real engine you will receive. An inspection certificate for the unit can travel with the order when you ask for it.

When you look at a listing, check the recorded mileage, the year and the photos of the ports and the stamp. Ask for photos of anything you want to see closer. Ask the desk for more pictures of any listing. We are happy to show the stamp, the ports and the ancillaries before you decide.

On a petrol engine like the M54B25, a careful fitter will also look at the spark plugs, the coils and the timing side before the engine goes in.

If the engine fails inside under normal use, the warranty covers you. 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.

See all M54 Engines · Search M54B25 in the shop

What should I replace when I fit a used M54B25 engine?

A used engine lasts longest when it starts life in your car with fresh fluids and new seals. 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. Change the drive belt, the thermostat and the water pump seals if they look tired, because they are cheap while the engine is out. 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 M54 Engines · Search M54B25 in the shop

How much does a used BMW M54B25 engine cost?

A used BMW M54B25 engine in our yard usually costs between 1.300 € and 2.200 €. The exact price depends on the year, the mileage and the parts that come with the engine.

Our units show recorded mileage from about 22,000 km up to around 200,000 km. Lower mileage and more ancillaries mean a higher price. Each listing shows its own price, and the price you see is the price you pay. Prices include VAT for private buyers.

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. If you order a gearbox or a second engine on the same order, the fee is still charged once.

Inside the EU there is no import duty. For the UK and other non-EU countries, import duty and local VAT are paid by the receiver, and we supply a commercial invoice.

See all M54 Engines · Search M54B25 in the shop

Will the M54B25 engine fit my BMW E85 Z4 2.5i?

Yes, if your BMW E85 Z4 2.5i was built with the M54B25. BMW used this 2.5 liter (2,494 cc) petrol engine with 141 kW (192 HP) in the E85 Z4 2.5i from about 2000 to 2006.

In our records the M54B25 is the engine for the E85 Z4 2.5i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E85 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 M54 Engines · Search M54B25 in the shop

Will the M54B25 engine fit my BMW E39 525i?

Yes, if your BMW E39 525i was built with the M54B25. BMW used this 2.5 liter (2,494 cc) petrol engine with 141 kW (192 HP) in the E39 525i from about 2000 to 2006.

In our records the M54B25 is the engine for the E39 525i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E39 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 M54 Engines · Search M54B25 in the shop

How much is a replacement M54B25 engine for a BMW E60 525i?

A used M54B25 for the BMW E60 525i costs from about 1.300 € to 2.200 € 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 M54B25 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 M54 Engines · Search M54B25 in the shop

How much power and torque does the BMW M54B25 have?

From the factory the BMW M54B25 makes 141 kW (192 HP) and 245 Nm of torque. It is a 2.5 liter (2,494 cc) inline 6, DOHC, 24 valve petrol engine with no turbo (naturally aspirated).

Without a turbo, the power builds smoothly with the revs. A clean air intake, healthy ignition and the correct fuel are key to getting the full figure.

A used engine reaches its factory numbers when it is fitted with the matching engine computer and software, and serviced with the right oil and filters. If the engine computer from your car is a different version, a specialist may need to code it.

Every M54B25 on our site lists its year and mileage. You can ask for extra photos, a close-up of the code stamp or a short video before you order.

See all M54 Engines · Search M54B25 in the shop

Will the M54B25 engine fit my BMW E46 325i?

Yes, if your BMW E46 325i was built with the M54B25. BMW used this 2.5 liter (2,494 cc) petrol engine with 141 kW (192 HP) in the E46 325i from about 2000 to 2006.

In our records the M54B25 is the engine for the E46 325i, which makes the match simple. Still, check the code on your old engine or send us your VIN.

Also tell us if your E46 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 M54 Engines · Search M54B25 in the shop

Delivery, warranty and payment

Every 325i 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.

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 E46 engines · M54 engine guide · BMW 325i engines for sale · Send us your VIN