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BMW 6 Series 630i S Cabrio common faults.

2004–2007, convertible, petrol, 258 HP.

The fault list covers: N52B30 engine, GM5L40, ZF6HP-BMW, ZF6HP26 transmission.

What you save stays on this device only. My saves

7 fault write-ups. All are important. 3 recalls.

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

Before you buy

Known faults

7 important faults

critical2

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

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

expensive5

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 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

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

In the ZF six speed automatic (BMW codes GA6HP19Z / GA6HP26Z) the electrical connector of the valve body control leaves the gearbox housing through a plastic sleeve. That sleeve and its seals age, and they let oil through.

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The symptom is irregular shifting, a gear slipping at higher revs, limp mode, a drivetrain fault code and a message on the display. The cause is the same in each case: the leak drops the hydraulic pressure, and the valve body cannot close the clutches with enough force.

The sleeve can be replaced without removing the gearbox, you only have to drop the oil pan. If it leaks for a long time, the slipping clutch and the overheating pump take the inside of the gearbox with them, and from then on it is a rebuild. The factory calls the oil a lifetime fill, but in practice the sleeve wears out around 60,000 to 70,000 miles, roughly 100,000 to 115,000 km.

between 100,000 and 200,000 km

What to check

  • On a lift look at the right side of the gearbox housing, above the oil pan: a wet, oily connector is the characteristic picture
  • On the test drive watch the shifts cold and warm: jerking, delay, slipping at higher revs
  • Ask for a fault code read from the gearbox controller: gear ratio fault, pressure regulation
2 more steps in the write-up

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

Checklist

BMW 6 Series 630i S Cabrio

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

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

Official recall3 recallsShow

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

A12/0202/17Safety recallInjuriesno date · EU Safety Gate

The universal joint of the drive shaft might break, causing a sudden loss of propulsion.

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

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

A12/02573/24Safety recallInjuriesno date · 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: Unknown

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

A12/1067/19Safety recallFireno date · EU Safety Gate

The battery positive (B+) transfer point in the boot may corrode. This can result in increased contact resistance, potentially leading to malfunction of the power supply and increased risk of fire.

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

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

Engine and transmission

1 engines · 3 transmissions

N52B30 · 3.0si/xDrive30i

190 kW (258 HP) · petrol

GM5L40 · 5-speed automatic, longitudinal (GM 5L40-E / A5S 360R)

automatic · 5 speed

Torque limit400 Nm
MakerGM

We built the code from the model and the gear count. The factory sheet does not state it. More than one transmission is possible. The gear count does not tell them apart. The code is on the side of the transmission.

Variant data

What is in this version

Factory data

Trim
630i S Cabrio
Body
convertible
Fuel
petrol
Transmission
automatic
Engine size
2996 cc
Power
190 kW (258 HP)
Drive
RWD
Production
2004–2007

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

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