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BMW 3 Series 318i Touring common faults.

2019–2022, estate, petrol, 156 HP.

The fault list covers: B48B20U1 engine.

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5 fault write-ups. 4 important. 7 recalls.

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

Before you buy

Known faults

4 important faults

critical2

B48 and B38 petrol: the timing chain guide rail breaks

critical

Plastic guide rails hold the timing chain in place. On these engines the plasticiser in the plastic leaches out over time, the rail turns brittle and then breaks into pieces. The pieces land around the chain and further down, in the oil sump and on the strainer of the oil pump, and the leached plasticiser also deposits on that strainer. Two kinds of damage come from this: without its guide the chain starts to flap, and less oil reaches the engine through the narrowing strainer. The first sign is a rattling noise on a cold start that goes quiet after a few seconds or once the engine has warmed up. It is heard best on a fully cold start in the morning, because the chain tensioner needs time to tension the chain. The problem is reported above 60,000 km. Replacing the chain costs between 700 and 2,900 euro, and is typically four figures, because the chain can only be reached by removing several engine components.

above 60,000 km700–2,900 EUR

What to check

  • Start the engine fully cold in the morning and listen for the rattling noise
  • Ask whether the chain and the guide rail have been replaced, and ask for the invoice
  • Ask when the oil was last changed and how often the car was serviced
2 more steps in the write-up

Electric water pump: silent failure, immediate overheating

critical

In these engines the water pump is not belt driven but has its own electric motor. It gains on fuel consumption, but it opens a new failure path: the pump or its electronics often simply stops with no warning. Measured in the official complaints, the typical mileage is 161,000 km (a tenth of the complaints already at 81,000, a tenth only above 257,000 km). So the common wisdom of "around 100,000 km" is early: most of the failures happen between 130,000 and 250,000 km.

Show the rest

With a belt driven pump the flow weakens gradually, here the circulation stops in an instant. In urban traffic the temperature crosses the limit within minutes, the cylinder head distorts, and the repair is an engine rebuild.

Replacing a still good pump at around 120,000 to 150,000 km costs less than repairing an overheated engine. If the replacement is already in the service book, the pump has already been changed.

between 81,000 and 257,000 km

What to check

  • Watch the coolant temperature gauge after startup: it should settle evenly, not jump around
  • Standing still with a warm engine, listen for whether the cooling fan and the pump are working
  • Ask for a fault code read: codes pointing at coolant flow belong here
2 more steps in the write-up

expensive2

Oil filter housing gasket: oil leak onto the belt and the alternator

expensive

A rubber gasket seals the oil filter housing to the block. The gasket hardens over the years, and oil leaks from under the housing. The oil drips onto the drive belt and the alternator.

Show the rest

Three things can happen. The oil stretches the belt and it can jump off (on a single belt engine that means an instant loss of the water pump and the alternator); oil getting into the alternator destroys the windings; and oil reaching the hot exhaust smokes and gives a burnt smell, and the official complaints do include burning smells and smoke.

The leak is visible: five minutes on a lift settles it. The gasket itself is a cheap part; the labour, the ruined belt and the alternator take the money.

between 64,000 and 246,000 kmreported complaints only

What to check

  • On a lift look at the block surface around the oil filter housing: a wet, oily or oily dusty film
  • Look at the drive belt: an oily, cracked, stretched belt is the consequence of the leak
  • Look at the alternator housing from below: an oil trail indicates damage reaching the windings
2 more steps in the write-up

Crankcase ventilation (CCV) in the valve cover: oil consumption, rough running

expensive

The crankcase ventilation leads the gas that forms in the crankcase back to the intake and separates the oil out of it on the way. If the system clogs or the membrane tears, the pressure cannot get away: it finds a way out past the seals, or it pushes the oil through the piston rings. This is where the oil consumption comes from, and the oil that appears around the valve cover gasket. In the other direction a faulty breather takes unmetered air into the intake, and that is what makes the idle rough, the throttle response hesitant and the running coarse. Starting also gets harder, and in an extreme case the engine stalls at idle. Two characteristic signs help: weak or absent suction at the oil filler with the engine running, and noticeably rough running around 3,000 rpm. The hose at the rear of the valve cover can also let oil out. The sound insulation then soaks itself with oil, and oil gets everywhere in the engine bay. On the six-cylinder engines the breather is built into the valve cover, so the repair is replacing the cover or the whole oil separator together with the hoses, between 80 and 900 euro.

between 80,000 and 150,000 km80–900 EUR

What to check

  • With the engine running unscrew the oil filler cap: weak or absent suction is a sign
  • Look around the valve cover and at the rear of the engine bay for oil traces
  • Watch the idle, and the rough running around 3,000 rpm
2 more steps in the write-up

cheap repair1

Plastic charge pipe: it goes brittle and cracks at the throttle body

cheap repair

The maker builds the charge pipe out of plastic, and the coupler at the throttle body is the critical point. The material goes brittle from heat cycles, from boost pressure and from the heat of the engine bay, and then it cracks. Three things coincide here: the moulded coupler carries both pressure and movement, the vibration of the engine arrives here through the throttle body, and the spot gets continuous heat load. The crack starts on the inner radius of the coupler. The symptom is a loss of pressure under load: the engine pulls cleanly at part throttle but flattens out at full throttle, and a hissing noise is audible from the engine bay at the same time. A yellow drivetrain warning comes with it, which often disappears after a restart, and sometimes a brief limp mode. One thing is worth knowing: a clean fault memory does not rule the crack out. The pipe has no sensor of its own, so the control unit can only log a boost pressure fault, and the leak is intermittent, appearing only under load. At a viewing two things are visible without tools. On the inner radius of the coupler the hairline crack sometimes comes with dark staining, because the oil mist in the boost air escapes through it. For the same reason a greasy, dark ring can appear at the joint of the coupler. The crack is reported above 80 000 kilometres, and replacing the pipe costs between 100 and 400 euros, because the part itself is not expensive. The most common misdiagnosis against that is replacing the turbocharger, which costs an order of magnitude more, and a pressure test protects against it. The factory repair is the same plastic part, which can crack again at a similar mileage; replaced with an aluminium pipe this failure mode disappears, and the driveability does not change.

above 80,000 km100–400 EUR

What to check

  • Look at the inner radius of the coupler at the throttle body: the hairline crack sometimes comes with dark staining
  • Look for a greasy, dark ring at the joint of the coupler
  • On a motorway slip road at full throttle watch for the loss of pressure and the hissing noise
2 more steps in the write-up

Checklist

BMW 3 Series 318i Touring

First what you would check on any car. Then the faults of this model.

Before you buy

Checklist

The printed sheet starts with what you would check on any car. What you tick stays on this device only.

On every car

Ask the owner

Faults of this model

vinkodex.com · Before you buy it, see what can go wrong.

Official recall7 recallsShow

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

Most recent: 7 July 2026

SR/02180/26Safety recallFire7 July 2026 · EU Safety Gate

The RSW22 starter with reinforced water tightness (RWT) may experience increased abrasion of the magnetic contact, causing deposits to build up at the lowest point inside the relay. These deposits may increase relay contact resistance, leading to starting failures or short circuits. If a short circuit occurs, either when attempting to start the vehicle or while driving due to vibration-related movement of the deposits, it could cause a thermal event and increase the risk of fire. 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: 07/07/2026

The authority's notice

SR/00551/26Safety recallFire30 January 2026 · EU Safety Gate

The failure concerns the RSW22 starter, type RWT (reinforced for watertightness). Increased abrasion of the magnetic contact can lead to the formation of deposits at the lowest point of the relay interior. This in turn can increase the resistance of the relay contact, causing accidental ignition or even short circuits, possibly leading to a thermal reaction and fire. 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: 30/01/2026

The authority's notice

SR/00568/26Safety recallFire30 January 2026 · EU Safety Gate

The failure concerns the RSW22 starter, type RWT (reinforced for watertightness). Increased abrasion of the magnetic contact can lead to the formation of deposits at the lowest point of the relay interior. This in turn can increase the resistance of the relay contact, causing accidental ignition or even short circuits, possibly leading to a thermal reaction and fire. 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: 30/01/2026

The authority's notice

SR/00569/26Safety recallFire30 January 2026 · EU Safety Gate

The failure concerns the RSW22 starter, type RWT (reinforced for watertightness). Increased abrasion of the magnetic contact can lead to the formation of deposits at the lowest point of the relay interior. This in turn can increase the resistance of the relay contact, causing accidental ignition or even short circuits, possibly leading to a thermal reaction and fire. 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: 30/01/2026

The authority's notice

A12/00976/22Safety recallFire, Injuriesno date · EU Safety Gate

The micro gas generator inside the seat belt retractor may not have been manufactured to specifications. This may lead to an impairment of the restraint function in case of an accident, increasing the risk of injury. Moreover, there may be spark formation in case of a pressure release outside of the inflator damaged tube, increasing the risk of fire. 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: Unknown

The authority's notice

A12/01377/22Safety recallFireno date · EU Safety Gate

Defects in the winding of cell-internal foils in the high-voltage batteries can lead to the occurrence of increased self-discharge. This can cause high voltage cell modules to overheat, increasing the risk of fire. 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: Unknown

The authority's notice

A12/01718/22Safety recallInjuriesno date · EU Safety Gate

The front safety belt on the left side may be faulty. This can increase the risk of injury in the event of an accident. The product does not comply with the requirements laid down in 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: Unknown

The authority's notice

Engine and transmission

B48B20U1

115 kW (156 HP) · petrol

We built the code from the model and the gear count. The factory sheet does not state it.

Variant data

What is in this version

Factory data

Trim
318i Touring
Body
estate
Fuel
petrol
Transmission
manual
Engine size
1998 cc
Power
115 kW (156 HP)
Drive
RWD
Production
2019–2022

Factory service interval

The manufacturer specifies this for this version. Of the mileage and the time, the one that comes first is the one that counts.

  • Air filter

    • 60,000 km or 4 years

  • Cabin (pollen) filter

    • 30,000 km or 2 years

  • Brake fluid change

    • first: 3 years, then 2 years(first change at 3 years, then every two years)

  • Engine oil and oil filter (BMW condition-based service)

    • LongLife25,000 km or 2 years

  • Spark plugs, petrol

    • 60,000 km or 6 years
All G20 versions

Information, not an expert opinion

We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.

  • A fault on the list does not mean the car you are looking at has it.
  • A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
  • You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.
Details in the terms