BMW X4 X4 M40i common faults.

2014–2018, SUV, petrol, 360 HP.

The fault list covers: N55B30 engine, ZF8HP transmission.

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10 fault write-ups. 9 important. 10 recalls.

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

Before you buy

Known faults

9 important faults

critical2

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.

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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

N52 / N55: aluminium bolts of the VANOS housing can loosen

critical

Four aluminium bolts hold the housing of the variable valve timing (VANOS). On some six cylinder engines built between late 2009 and mid 2012 these bolts loosen over time, and can also break.

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If the housing moves, the timing becomes imprecise: the engine runs roughly, loses power, can drop into limp mode, and rarely can stall. That is why the maker started a safety recall (NHTSA 23V-707).

The recall covers the N51 / N52K / N52T / N55 engines; Their codes are N52B25, N52B30 and N55B30. The repair is replacing the four bolts; if a bolt is already broken or loose, the whole VANOS unit has to be replaced.

"No recall letter arrived" is not enough: ask at the workshop whether the repair code 0011520700 appears in the history.

between 134,000 and 300,000 km

What to check

Ask for the build date: the recall covers production between September 2009 and July 2012
Ask for the service history and look for the VANOS bolt / 0011520700 recall being carried out
On a cold start watch for rough running, jerking and loss of power

2 more steps in the write-up

expensive7

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.

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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

VANOS solenoid valve: a clogging filter screen and late camshaft adjustment

expensive

VANOS adjusts the position of the camshaft with the pressure of the engine oil, and a solenoid valve metres that pressure. The valve sits in the oil circuit, and a fine filter screen protects the spool inside it from larger particles. That screen clogs with carbon and deposits: less oil flows through, and VANOS then adjusts late or does not move at all. The symptoms are a rough idle, rough running, a lack of torque at low revs and higher fuel consumption, because the valve timing is off. A short metallic clacking can also come on a cold start and goes quiet after 10 to 20 seconds. The engine warning light comes on with a camshaft fault code, and depending on the severity the engine control unit switches to limp mode. The fault code narrows down the cause. P0010 and P0013 typically mean the solenoid valve itself, that is a circuit fault or reduced oil flow through the clogged screen. P0011 and P0014 point more to a mechanical cause: a stretched timing chain or a worn adjuster. P0012 and P0015 report late camshaft control, whose common cause is slow pressure build-up at the adjuster, so again the dirty valve. The valve itself is a small part, between 50 and 120 euro, and with a clean screen cleaning is often enough; replacing the whole adjuster, by contrast, is a four-figure job. The reported repairs ran between 80 and 1,200 euro, depending on whether cleaning is enough and how many valves are affected. The main cause of the screen clogging is a stretched oil change interval and carbon-laden oil.

between 70,000 and 120,000 km80–1,200 EUR

What to check

Read the fault memory and note the exact code: P0010 and P0013 point to the valve
If P0011 or P0014 is stored, the timing chain has to be checked as well
Start the engine cold and listen for metallic clacking in the first 10 to 20 seconds

2 more steps in the write-up

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

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

N54 / N55: high pressure fuel pump

expensive

This is the most common N54 fault, and it affects early N55 engines too. The pump is a two part design: fuel goes into one half and lubricating oil into the other, and the sealing ring separating them ages over time. That is what drops the pressure.

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The very first symptom is a long crank: the engine does not catch straight away but turns over for several seconds. Later you get a rough idle, misfire, loss of power, and finally limp mode, which can reach you at the side of the road.

The fault code is typically P0087 or P0089. If the control unit also returns a camshaft timing code (P0011, P0012), that is often not a separate fault but a consequence of the pressure drop: it is worth ruling the pump out first.

The 2007 to 2009 cars are the worst; the maker revised the design after that.

The N53 (the lean burn six cylinder sold in Europe) got the same pump. Faults were reported on it. It is not known whether they are as frequent as on the N54, because the N53 was not sold in the USA and there is no official complaint data on it.

between 114,000 and 256,000 km

What to check

Cold start: the engine must catch straight away. Several seconds of cranking is the first sign
Restart it once or twice when warm too, and watch for the same thing
Load the engine on the test drive: jerking, loss of power and limp mode are suspect

2 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

Valvetronic: oil in the sensor connector, a worn eccentric shaft

expensive

Valvetronic adjusts the lift of the intake valves, and an eccentric shaft does that work. Three parts can fail here, at very different prices, and their symptoms are nearly identical.

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The sensor is usually the first to give up: oil leaks past its seal into the connector, and the oil corrupts the signal the engine control unit depends on. From then on the control unit gets no reliable position feedback, cannot set the valve lift precisely, and switches to a protective strategy. The fault code in this case is a plausibility fault, 2A67 or 2A6B: the control unit does not consider the position signal credible.

The eccentric shaft itself can also wear out or seize, and there are several causes for that: lack of lubrication from oil sludge and skipped oil changes, wear of the bearings, a system driven on with a failed actuator motor, and overheating and oil contamination in the cylinder head. It is reported from 150 000 kilometres.

The symptom is similar in all three cases: an unstable idle, stumbling and long cranking at a cold start, a check engine light that comes on and goes out on its own, lack of power or limp mode, inconsistent throttle response, and misfires cylinder by cylinder. A clicking, binding noise from the engine bay points to a seizing shaft.

The misdiagnosis is common, because the symptom shows up at combustion, so coils and spark plugs are suspected first, while the fault is in the air control. The condition of the shaft can only be established after the valve cover has been removed and it has been inspected. The sensor connector, though, is worth opening up first: if it is oily, that is the far cheaper route.

above 150,000 km

What to check

Open up the connector of the eccentric shaft sensor: an oily connector means the cheaper fault
Watch the revs at idle: an unstable idle and misfires cylinder by cylinder belong here
Start it cold: stumbling and long cranking are symptoms

3 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

Official recall10 recallsShow

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

Most recent: 30 March 2023

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

16V333000CHILD SEAT:LATCH STRAPCHILD SEAT:LATCH STRAP23 May 2016 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain model year 2011-2017, X3 sDrive28i, X3 xDrive28i and X3 xDrive35i, vehicles manufactured July 2, 2010 to April 14, 2016, 2015-2017 X3 xDrive28d vehicles manufactured March 10, 2014 to March 31, 2016, and 2015-2017 x4 xDrive28i, X4 xDrive35i and X4 xDriveM40i vehicles manufactured March3, 2014 to April 15, 2016. The affected vehicles have lower anchor bars for securing child restraint seats that may become damaged when using the European-ISOFIX-type, rigid-style connector, child restraint system.

Risk: Damaged lower anchor bars may increase the child's risk of injury in the event of a crash.

Remedy: BMW will notify owners, and dealers will weld a reinforcing bracket to the lower anchor bars and the vehicle body, free of charge. The recall began on July 13, 2016. Owners may contact BMW customer service at 1-800-525-7417.

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

14V648000VISIBILITY:REARVIEW MIRRORS/DEVICES:EXTERIORVISIBILITY:REARVIEW MIRRORS/DEVICES:EXTERIOR16 October 2014 · NHTSA (USA)

BMW of North America, LLC (BMW) is recalling certain model year 2015 X3 and X4 Sports Activity Vehicles manufactured July 28, 2014 to July 29, 2014. The affected vehicles may have been produced with a driver's side exterior rearview mirror that was designed to meet non-US market requirements. Thus, these vehicles fail to comply with the Federal Motor Vehicle Safety Standards No. 111, "Rearview Mirrors."

Risk: The driver may not notice that vehicles viewed in the mirror are closer than they appear, increasing the risk of a crash.

Remedy: BMW will notify owners, and dealers will replace the driver's side exterior rearview mirror, free of charge. The recall began on December 16, 2014. Owners may contact BMW customer service at 1-800-525-7417 or CustomerRelations@bmwusa.com.

We could not check this: model year. 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.