BMW X4 X4 xDrive20d common faults.

2018–2021, SUV, diesel, 190 HP.

The fault list covers: B47D20 engine, ZF8HP transmission.

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5 fault write-ups. All are important. 11 recalls.

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

Before you buy

Known faults

5 important faults

critical3

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

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

expensive2

XDrive transfer case (ATC): binding in corners, plastic actuator gear

expensive

The heart of the four wheel drive in the longitudinal engine BMW X models (X3, X5 and the X1 E84) is the ATC transfer case. It has two faults, and you can feel both while driving.

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The first is wear of the clutch pack and the fluid: in a slow, tight corner (a car park, a roundabout) the car jerks and "hops", as if the drive grabbed and let go. You can also get a jerk when pulling away on a slope. The second is the plastic actuator gear: the position signal is lost, the brake, ABS and 4x4/DSC lights come on together on the dash, and a clicking is audible from the transfer case when you switch the ignition off.

Workshops often propose a full transfer case replacement straight away. But the plastic gear can be replaced on its own, and the wrong tyre size or a mixed set of tyres also imitates the jerking, because the transfer case then slips continuously. So clear up the tyres and the fault code first, before you pay for a transfer case replacement.

between 72,000 and 175,000 km

What to check

In a slow, tight corner (a car park) watch for jerking, binding and a "skipping" feel
When pulling away on light throttle, can you feel the drivetrain jerk
Watch the dash: 4x4, ABS, DSC and brake lights together point at the actuator

4 more steps in the write-up

ZF 8HP automatic: mechatronics unit and connector sleeve leak

expensive

The ZF eight speed automatic (BMW Steptronic 8HP family) has two faults, and you can feel both.

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The first is the mechatronics unit: the valve body and the control electronics in one. If the solenoids or the pressure regulation weaken, the gearbox jerks, the D/R engagement is delayed, it logs a gear ratio fault code, and finally drops into limp mode (often staying in 2nd or 3rd).

The second, and often misdiagnosed, is the connector sleeve of the mechatronics unit: the O-ring of the plastic sleeve ages, and ATF leaks from the side of the housing, exactly where the wiring harness enters. This is easy to mistake for a rear crankshaft seal. The trail starts from the driver's side of the housing, not from the clutch side.

On cars built in 2023 there was also a separate safety recall for a welding fault in the mechatronics unit. That is not the same as the wear related sleeve and the valves.

Check the fluid level, the area around the sleeve and the fault codes first; do not accept a "full gearbox replacement" quote straight away.

above 120,000 km

What to check

On the test drive watch for delayed D/R engagement, a jerk when shifting, and limp mode (a stuck gear)
Look at the driver's side of the gearbox housing where the wiring harness enters: an ATF trail from the sleeve is suspect
Do not confuse it with a rear crankshaft seal leak: the direction of the trail decides

3 more steps in the write-up

Official recall11 recallsShow

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

Most recent: 8 July 2021

21V521000AIR BAGS:FRONTALAIR BAGS:FRONTAL8 July 2021 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain 2018-2019 X3 sDrive30i, X3 xDrive30i, X3 M40i and 2019 X4 xDrive30i, and X4 M40i vehicles. The front passenger seat occupant classification system may have been improperly assembled, which could result in the misclassification of the seat as unoccupied, and deactivate the front air bag.

Risk: A deactivated front air bag will not deploy in the event of a crash, increasing the risk of injury.

Remedy: Dealers will replace the seat foam, which includes the occupant classification system, free of charge. Owner notification letters were mailed on September 3, 2021. Owners may contact BMW customer service at 1-800-525-7417.

The authority's notice

20V152000ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANELELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL18 March 2020 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain 2019-2020 X4 xDrive30i and X4 M40i, and 2018-2020 X3 sDrive30i, X3 xDrive30i, X3 M40i, and X3M vehicles. The instrument panel casing may not have been tightened properly to the passenger air bag.

Risk: In the event of a crash necessitating air bag deployment, the air bag could damage the instrument panel and cause small pieces of the panel to strike the driver or other occupants, increasing the risk of injury.

Remedy: BMW will notify owners, and dealers will replace the instrument panel casing, free of charge. The recall began May 15, 2020. Owners may contact BMW customer service at 1-800-525-7417.

The authority's notice

19V563000SEATSSEATS31 July 2019 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain 2018-2019 X3 sDrive30i, xDrive30i and M40i and 2019 X4 xDrive30i and M40i vehicles. The front seatback frames may have been improperly welded, allowing the seatback to unexpectedly fold forward or rearward.

Risk: In the event of a crash, there is an increased risk of injury if the seatback folds forward or rearward.

Remedy: BMW will notify owners, and dealers will replace the front seats, free of charge. The recall began September 27, 2019. Owners may contact BMW customer service 1-800-525-7417.

The authority's notice

19V291000AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULEAIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE10 April 2019 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain 2019 X3 sDrive30i, X3 xDrive30i, X3 M40i, and X4 M40i vehicles. The instrument panel assembly may have been improperly manufactured, possibly affecting the deployment of the passenger's frontal air bag.

Risk: If the front passenger air bag does not deploy properly in the event of a crash, the occupant has an increased risk of injury.

Remedy: BMW will notify owners, and dealers will replace the instrument panel assembly, free of charge. The recall began June 3, 2019. Owners may contact BMW customer service at 1-800-525-7417.

The authority's notice

18V453000SERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:DISC:CALIPERSERVICE BRAKES, HYDRAULIC:FOUNDATION COMPONENTS:DISC:CALIPER6 July 2018 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain 2018-2019 BMW X3 sDrive30i, X3 xDrive30i, X3 M40i and certain 2019 X4 xDrive30i and X4 M40i vehicles. The rear brake caliper pistons on these vehicles may have an insufficient coating, potentially reducing rear brake performance.

Risk: A reduction of braking performance can increase the risk of a crash.

Remedy: BMW will notify owners, and dealers will bleed the rear brake circuit, free of charge. The recall began August 31, 2018. Owners may contact BMW customer service at 1-800-525-7417.

The authority's notice

A12/00608/20Safety recallInjuriesno date · EU Safety Gate

The screw connection from the passenger's airbag to the instrument panel may not have been manufactured according to specifications. As a result, if the airbag is activated, the panel cover may break into pieces, which will be propelled against the passenger increasing the risk of injury.