BMW 3 Series 318d common faults.

2012–2015, saloon, diesel, 143 HP.

The fault list covers: B47D20, N47D20 engine, GS6 transmission.

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6 fault write-ups. All are important. 16 recalls.

If you know the year, pick it. Faults for other years drop out of the list.

Before you buy

Known faults

6 important faults

Diesel high pressure pump: power loss and engine shutdown while driving

critical

The high pressure pump of these common rail diesels (Bosch CP4) can fail while driving. The characteristic course is not gradual: a "Drivetrain fault" message appears on the dash, and within a few seconds the power is gone, on the motorway too. Afterwards the engine often cranks but will not start.

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What makes the repair expensive: once the inside of the pump wears, metal debris travels through the rail and contaminates the entire fuel system. At that point replacing the pump is not enough: the injectors, the rails, the tank and the lines go with it. That is the difference between a "pump replacement" and a "full system replacement" quote, that is what you should ask about.

The maker started a recall for this in the United States (NHTSA 21V586000, 2014 to 2018 328d / X5 xDrive35d / 535d / 740Ld / X3 xDrive28d). The same campaign did not run in Europe, even though the same pump works in the 320d/520d/X3 20d versions that are common right across Europe. The recall does not cover these cars.

between 79,000 and 248,000 km

What to check

Ask whether there has ever been a "Drivetrain fault" message or a loss of power while driving
Ask for the service history: if the high pressure pump was replaced, check whether the injectors and the lines were replaced with it. If not, the debris may still be in the system
After a cold start listen to the engine at idle: irregular running or smoke is suspect

3 more steps in the write-up

N47 / N57 diesel: timing chain on the rear of the engine

critical

In these diesels BMW put the timing chain at the back of the engine, on the gearbox side. The chain, the guides and the tensioner wear early. The symptom is a metallic rattle on a cold start that quietens once warm.

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The engine or the gearbox has to come out for the replacement, so the labour is a multiple of the parts cost. If the chain breaks or jumps, the engine is badly damaged inside, and the repair is an engine rebuild.

The problem is worst on engines built between March 2007 and March 2011, and the ones before early 2009 are the worst of all. The maker handled it under a service campaign in several European markets, but in the United Kingdom there was no formal recall. "It was never recalled" does not mean the chain is fine.

According to the German technical press the fault affects the whole N47 series and every power output, inspection is advised from 100,000 km, and factory revisions closed the matter around 2013, so cars built after 2013 are in a significantly better position. Stretching is typically preceded by a distinct rattle.

between 100,000 and 200,000 km

What to check

Insist on a cold start: the car should stand overnight, and the seller must not start it before you arrive
At the moment of starting, stand behind the engine (on the gearbox side) and listen to the first 3 to 5 seconds
A metallic rattle from the back of the engine calls for immediate expert inspection: this is not "diesel noise"

2 more steps in the write-up

Diesel EGR cooler: cracking, coolant in the intake, fire risk

critical

The internal fins of the exhaust gas recirculation cooler crack over time, and glycol coolant leaks into the intake, where it mixes with soot. The sticky mixture can ignite at high temperature: it can melt the plastic intake manifold and, in extreme cases, cause an engine bay fire.

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The maker recalled the 2013 to 2018 four and six cylinder diesels, roughly 800,000 cars worldwide. The first repair attempt proved insufficient, and the leak returned in several cases: the cooler fitted since 2022, from a different supplier, is the valid fix.

So "the recall was carried out" is not enough on its own: you have to check when, and which repair was done. A first round repair does not by itself rule the problem out.

The early symptoms are white, sweet smelling exhaust smoke, slowly dropping coolant, and a rough idle.

It shows up on diesels built between 2013 and 2018. The earlier M57 is not covered by the recall.

between 108,000 and 222,000 km

What to check

Check the level in the expansion tank, and ask whether it has needed topping up
After a cold start watch the exhaust: persistent white smoke and a sweet smell mean the coolant is burning
Ask for the service book and find the EGR cooler recall entry: Check the date too

2 more steps in the write-up

B47 diesel: the timing chain stretches on the early model years

critical

On the early model years the timing chain of the B47 stretches faster than intended. The chain tensioner compensates for the stretch for a while and then no longer can: the chain jumps, the valve timing goes off, and in a severe case engine damage follows. The first sign is a rattling, clacking noise on a cold start that goes quiet after one to three seconds. On the B47 the chain sits at the front of the engine, not at the rear as on its predecessor, the N47. The replacement is therefore considerably less, between 1,200 and 1,800 euro, against 2,000 to 2,500 euro on the N47; if the chain has already jumped, the repair can run up to 4,500 euro. The risk is highest on units built before the end of 2015, with a reported rate of 3 to 5 per cent. 2016 was better but cases remained, and between July and December 2016 an improved chain tensioner was phased in. After mid-2016 the problem is rare, below one per cent. The engine has been in almost every four-cylinder diesel BMW since 2014, from the 1 Series to the 5 Series and from the X1 to the X4. The build date therefore says more here than the model.

above 120,000 km1,200–4,500 EUR

What to check

Start the engine cold and listen for the rattling noise in the first seconds
Ask for the build date, because units built before the end of 2015 are the risky ones
Ask whether the chain or the tensioner has been replaced, and ask for the invoice

2 more steps in the write-up

B47 / B57 diesel: particulate filter and turbo on short trips

critical

The B47 replaced the N47, and the maker fixed the timing chain problem. The two remaining risks on this modern diesel depend on how the car was used.

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The first is the particulate filter. On short urban trips the regeneration cannot finish, and the filter clogs. The second is the turbo. With extended oil change intervals its bearings wear.

On this engine the service history and the type of use tell you more than the odometer. On a 200,000 km car driven on motorways and serviced often, the filter and the turbo can be in better shape than on a 90,000 km city-only car.

Where turbo wear leads in the worst case: a runaway engine. If the turbo shaft seal fails, engine oil enters the intake on the compressor side. A diesel burns that too, and this is different from a petrol engine: a diesel controls torque with the quantity of fuel injected, and it has no throttle. Once the engine runs on its own oil, cutting the injection and switching off the ignition will not stop it. The revs climb on their own until the engine destroys itself for lack of lubrication.

If this happens while driving, turning the key does not help. The only thing that works is cutting off the air: cover or plug the intake, or discharge a dry powder extinguisher into the intake tract. On a manual car you can also stall it: hold the parking brake and the brake pedal, select a high gear, and release the clutch quickly so the drivetrain chokes the engine.

This is not common, and it can happen on any turbo diesel, not only on this engine. On this engine the turbo bearing and seal wear. The warning signs are blue smoke under acceleration, an unexplained drop in oil level, and an oily charge air pipe.

What to check

Ask how the car was used: short daily trips or longer runs?
Read the fault codes for particulate filter regeneration and differential pressure
On a longer test drive watch the power delivery and the smoke under load

5 more steps in the write-up

F30: electric power steering dropping out

critical

On the electric power steering built from 2011 a recurring complaint is the assistance dropping out intermittently: the steering goes heavy while driving, then comes back after an ignition cycle. Over time it stops coming back, and the assistance is gone for good.

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The cause is often the steering rack's own control unit or the torque sensor. If the control unit does not communicate, diagnostics often returns no fault code at all, so "no fault code, so nothing is wrong" is wrong. If the assistance drops out while driving, the steering goes heavy, and you should have it checked the same day.

What to check

Standing still with the engine running, turn the wheel lock to lock: the assistance should be even
On the test drive watch whether the steering goes heavy, even for a moment
After switching the ignition on, check the dash: there should be no yellow or red steering icon

2 more steps in the write-up

Official recall16 recallsShow

The manufacturer fixes these for free at a franchised dealer. Ask with the VIN whether it was done.

Most recent: 31 August 2026

SR/02525/26Safety recallFire31 August 2026 · EU Safety Gate

Water may enter the starter motor and cause damage. As a result, the engine may no longer start, or the starter motor may short-circuit or remain continuously activated. This could cause local overheating of the starter motor or thermal overload of surrounding components and lead to a vehicle fire, including when the ignition is switched off. The product does not comply with the Regulation on the approval and market surveillance of motor vehicles and their trailers, and of systems, components and separate technical units intended for such vehicles.

Remedy: Type of economic operator taking notified measure(s): Manufacturer Category of measure(s): Recall of the product from end users Date of entry into force: 31/08/2026

We could not check this: model year. The authority's notice

SR/01940/26Safety recallInjuries19 March 2025 · EU Safety Gate

The propellant in the driver airbag may deteriorate over time. If the airbags deploy, it could result in fragments from the inflator injuring the vehicle's occupants. The product does not comply with the Regulation on the approval and market surveillance of motor vehicles and their trailers, and of systems, components and separate technical units intended for such vehicles.

Remedy: Type of economic operator taking notified measure(s): Manufacturer Category of measure(s): Recall of the product from end users Date of entry into force: 19/03/2025

We could not check this: model year. The authority's notice

A12/00868/23Safety recallInjuries30 March 2023 · EU Safety Gate

The airbag may deteriorate over time, and if deployed, excessive internal pressure may cause the inflator body to burst and metal fragments could pass through the cushion material causing injury to occupants. The product does not comply with the Regulation on the approval and market surveillance of motor vehicles and their trailers, and of systems, components and separate technical units intended for such vehicles.

Remedy: Type of economic operator taking notified measure(s): Manufacturer Category of measure(s): Recall of the product from end users Date of entry into force: 30/03/2023

We could not check this: model year. The authority's notice

A12/01929/23Safety recallInjuries29 June 2021 · EU Safety Gate

The propellant in the driver airbag can deteriorate due to high humidity and temperature variations. In the event of an accident in which the airbag deploys, this could result in fragments from the inflator casing coming loose and injuring the vehicle’s occupants. The product does not comply with the Regulation on the approval and market surveillance of motor vehicles and their trailers, and of systems, components and separate technical units intended for such vehicles.

Remedy: Type of economic operator taking notified measure(s): Manufacturer Category of measure(s): Recall of the product from end users Date of entry into force: 29/06/2021

We could not check this: model year. The authority's notice

A12/01930/23Safety recallInjuries29 June 2021 · EU Safety Gate

Remedy: Type of economic operator taking notified measure(s): Manufacturer Category of measure(s): Recall of the product from end users Date of entry into force: 29/06/2021

We could not check this: model year. The authority's notice

A12/00068/19Safety recallInjuriesno date · EU Safety Gate

The press-in force of the counterbalance shaft’s bearing shells may not have met the specifications, which could cause the counterbalance shaft to become loose. As a result, the engine could be damaged and locked in motion, increasing the risk of an accident.