11 Common BMW 6 Series Problems (Explained)

The BMW 6-Series is a sporty 2-door grand tourer that was originally introduced in 1976.

Being one of BMW’s larger and more expensive models, the 6-Series boasts distinctive styling, powerful engine options, a comfortable ride, and luxurious interiors.

In this article, we’ll take a look at the most common issues and problems 6-Series owners have encountered over the years.  

1. Excessive Oil Consumption 

The V8 engines in the second and early third generation BMW 6-Series have a tendency to burn lots of oil.

Excessive oil consumption typically affects the N62 and N63 engines found in the 2004 to 2012 model years of the 6-Series.

The third generation BMW M6 sold from the 2012 to 2018 model years used the S63 V8 engine which also burns a lot of oil.

By the 2013 model year, the BMW 650i started using the updated N63TU engine which had fewer oil consumption problems.

Here’s how a few owners on the 6Post.com forum described their issues:

“My 2008 650i Convertible looses lots of oil. I got 110k miles on it. Car runs great, no issues. I don’t see any oil leaks when car is standing, running or not. But I still find myself adding oil often (I would estimate 0.5 quart every 400/500 miles).”

“After I purchased my new 2016 M6GC I had the same problem. I was using about a quart of oil every 1,000 miles.”

For BMW, as well as many other manufacturers, losing 1 quart of oil every 1,000 miles is considered normal.

Most owners just regularly top up the oil when the oil level in the vehicle settings gets a little low.

If you want to prolong the life of your engine, don’t wait for the low oil warning to go off and keep at least  quart of oil in the car for emergencies.

If the car loses or burns an excessive amount of oil, check for leaks inside the engine bay and underneath the car.

If you’re not mechanically inclined, a dealer or a BMW specialist should be able to determine if the engine has any major problems that need to be addressed.

In cars with over 100,000 miles, the engine internals might have worn out enough to cause oil to leak into places where it shouldn’t go. 

The only way to fix this issue is to rebuild the entire engine to refresh all the seals and worn out engine components.

2. Worn Valve Stem Seals

Many higher mileage second and third generation examples of the BMW 6-Series will eventually have leaking valve stem seals which requires an expensive engine out repair.

This is a very common problem in the N62 and early N63 engines equipped in the 645i and 650i from 2004 to 2013.

The S63 engine used in the third generation M6 also suffers from this issue.

Problems usually show up after the car has passed 100,000 miles, but can occur at lower mileages if the car hasn’t been properly maintained.

Other BMW models that use the same engines like the X5, 5-Series and 7-Series also have similar issues.

Common symptoms of worn valve stem seals include:

• Bluish white smoke after idling for a while
• Excessive oil consumption
• Low oil warnings
• Premature catalytic converter failure

Here’s how two 6-Series owners described their experience on the BimmerFest.com forum:

I have a 2010 BMW 650i and it has been smoking from tail pipes for a couple months now which is believed to be my valve seal guides.

“I need help replacing the valve stem seals on my N62. It is a 2006 650i no SES light yet, and it runs like a charm…but I want to keep it that way. I have been seeing blue smoke at extended idle for about 7 months now, and wanted to wait until my oil consumption became noticeable. Well it is now starting to consume a bit of oil, and smoke isn’t yet horrible but I would like to take care of this before it wears on my cats.”

Replacing the valve stem seals can cost around $5,000 at the dealer to fix. 

Independent BMW specialists can usually do the job for around $2,500 which is still quite expensive.

3. Crankcase Ventilation Issues

The 650i from the third generation 6-Series can have premature failures of the crankcase ventilation lines.

This issue affects the 2013 to 2015 model years of the 650i with the updated N63TU engine the most. 

Higher mileage second and third gen models of the 650i and 645i can also eventually suffer from the same failures.

Common symptoms of a faulty crankcase ventilation system or CCV include:

• Suction sound when removing oil cap (engine running)
• Whistling sound from engine bay
• Reduced performance
• Rough idling
• Hard starting
• Oil in intake manifold
• Excessive oil consumption
• White smoke from exhaust
• Check engine light

Here’s how a few 6-Series owners on BimmerFest.com described their experience:

“I received a check engine light on dash along with “Increased emissions”. Fault codes fired: 29E8, 29F0, & 29EF Lean mixture faults, found both side crank case vent valves leaking air.”

“CCV valve on passenger side was torn. Replaced them both. The caps were hard to get off without breaking the brittle plastic but was able (the new caps didn’t have the hose nipple). Car now idles fine!”

“I had a very annoying loud whistling sound on my 05 645, and discovered that when I loosened the oil cap, which allowed air to enter the engine, the sound changed. I stumbled on this thread, did the rebuild on the CCV valves, and the noise is GONE! I am still getting the “increased emissions” service message, however, and was wondering about how to clear that.”

Due to the number of premature failures, BMW extended the warranty for the CCV valve and hoses to 10 years or 120,000 miles for the 2013 to 2015 model years of the 650i.

Other BMW models with the same N63TU engine also suffer from similar issues and have the same extended warranty.

If your vehicle isn’t part of the warranty extension, repairing the lines out of warranty isn’t too difficult and typically only costs a few hundred dollars.

4. Oil Leaks

Just like most BMW’s, the 6-Series can suffer from multiple oil leaks as it gets older.

It’s not unusual for the engine’s seals and gaskets to start leaking at 50,000 to 100,000 miles.

This issue affects all model years of the 6-Series, starting from the first generation up to the latest one.

Common sources of oil leaks in the modern 6-Series include:

• Valve cover 
• Oil filter housing 
• Alternator bracket
• Upper timing cover 
• Oil pan
• Front and rear main seal

The N62 engine of the second generation 645i and 650i are known for developing a leak on the alternator bracket seal or O-ring.

If this O-ring completely lets go while the car is running, you’ll have a massive oil leak on your hands.

Here’s how one owner described their experience on BimmerFest.com:

“Alternator oil bracket gasket on my 2005 645. I only have my car for a few months and love it. It started leaking oil under pressure, never in the drive way. Bimmer world is going to replace it for $350.00.”

Most common BMW oil leaks like the valve cover and oil filter housing gaskets aren’t very difficult to replace even for a novice mechanic.

Some gaskets like the one for the alternator bracket are much harder to replace and can cost as much as $2,000 if you have it done at a dealership.

An independent BMW specialist can usually do the same job for around $500 to $1,000.

If your car already has over 50,000 miles and you’re already taking it in to get an oil leak addressed, it’s a good idea to have the other gaskets replaced even if they’re not yet leaking so you can save on future repair costs.

Related: 17 Best & Worst BMW 6 Series Years (Facts & Stats)

5. Coolant Leaks

BMW uses a lot of plastic pipes for its coolant lines which are notorious for getting brittle and cracking even before the car reaches 100,000 miles.

Some of the more common sources of coolant leaks in lots of BMWs include:

• Hoses and pipes
• Expansion tank hose
• Reservoir
• Parts of the radiator
• Water pump
• Turbo coolant line

The N62 engine in the second generation 6-Series also has a tendency to develop coolant leaks at the coolant transfer pipe which is underneath the valley pan or the V-shaped cavity between the cylinder heads.  

This can be extremely troublesome as it basically requires tearing apart the upper part of the engine to replace the coolant transfer pipe.

The valley pan itself can also leak coolant.

This particular issue only affects the 650i and 645i from the 2004 to 2010 model years.

Here’s how one owner described their experience on BimmerFest.com:

“I had the transfer pipe leak problem on my 2004 645Cic with only 81,000+ miles on it. I used an independent BMW certified mechanic, and it took a full two days in the shop.”

Another user on BimmerPost.com had this to say:

“It’s been almost a year now into my 650i ownership, currently at 73k miles. Biggest issues so far were leaky coolant lines at the T connectors beside the charge pipe and turbo inlet.” 

Replacing the coolant transfer pipe can cost over $4,000 at the dealer, but several aftermarket companies have come up with solutions that make the repair easier.

That said, it can still cost over $1,000 if you have it done at an independent BMW specialist.

Once the car nears the 10-year mark, you’re going to see more and more cooling system component failures.

It’s a good idea to routinely check the coolant levels every few months and not wait for the low coolant warning to appear if you want to keep your engine in great condition. 

If the engine overheats, pull over and have it towed to avoid damaging it further.

6. Fuel System Issues

The third generation 6-Series can suffer from both premature high pressure fuel pump and fuel injector problems that affect the drivability of the vehicle.

These issues are mostly limited to the early models of the third gen 6-Series.

Early fuel pump problems only affect the 2012 model year 640i and 650i while fuel injector issues are common in the 2012 to 2015 models of the N63 powered 650i.

Symptoms of fuel pump or injector issues include:

• Engine stalling
• Rough running/idling
• Reduced power
• Misfiring
• Check engine light
• Drivetrain Malfunction error

Here’s how one owner on the BimmerFest.com forum described their experience:

“2012 N63 650i (Constant Injector Problems). Purchased this car back in March of 2014 (10K miles). The same day I bought the car, it broke down. Took it in to the shop, and it was the injectors. Dealership quickly replaced, and no problems. Fast forward to approx. Aug2015, I read about the N63 Customer Care Package, and take it in to the dealer to be serviced. The injectors, along with a few other things under the program were changed. On Oct 5, 2016 with 58K miles, the injectors failed again, and the dealer is trying to charge me $6,000 to replace.”

BMW extended the warranty for the fuel pump in the 2012 6-Series to 10 years and unlimited miles.

Replacing a faulty fuel pump out of warranty isn’t very expensive and is fairly easy for any mechanic. 

The fuel injectors in the 2013 to 2015 650i were also given an extended warranty of 10 years/120,000 miles.

A single injector costs around $200 to $300 so it can get expensive real fast if you need to replace all eight injectors.

If the injectors are just a bit dirty, you can try using a fuel system cleaner or having them professionally cleaned to save on repair costs. 

7. Radio and Electrical Problems

The second generation 6-Series can develop issues with the iDrive head unit as they get older.

The iDrive CCC or Car Communication Computer is a known weak point of the 6-Series and many owners have had to get it replaced.

Water can also leak into the trunk and damage the amplifier which cuts out all the sound from the infotainment as well as many of the vehicle’s notifications and warning sounds.

These head unit problems can affect all model years of the second gen 6-Series from 2004 to 2010.

In the 2004 to 2005 models, the Micro Power Module or MPM is also located in the trunk and can get shorted out by water leaks.

The MPM controls many of the car’s electronics such as:

• iDrive system
• Radio
• Lights
• Door locks
• Climate control

Here’s how a few owners described their experience with the 6-Series radio:

“I have an 04 645Ci convertible and there is no sound. The stereo works on the screen, but no sound.”

“I took the amp out and there has been water in there, but I have no idea how much or for for how long as I haven’t had the car that long.”

If your CCC stops working, you can get a new or used unit and have it reprogrammed for your car.

Due to the number of CCC failures, many shops have started specializing in refurbishing and repairing the defective units.

Starting with the 2006 model year, BMW also relocated the MPM behind the glove box which significantly improved the car’s reliability as far as the electronics are concerned.

8. Stretched Timing Chain

Early model years of the third generation 6-Series with the N63 turbo V8 can suffer from premature stretching of the timing chain.

Normally, the timing chain should last the entire lifespan of the vehicle or at least 200,000 miles before you need to start worrying about it.

However, BMW itself has stated that the timing chain in the early N63 engines can wear out and stretch prematurely.

A worn timing chain can cause issues such as:

• Misfires
• Engine rattles
• Premature valvetrain wear
• Reduced performance
• Sudden engine failure

BMW released a Customer Care Package, which is basically a comprehensive service bulletin, for many models equipped with the early versions of the N63 engine to address lots of problematic parts which includes the timing chain components. 

Only the 2012 to 2013 model years of the 6-Series are eligible for these fixes since the newer model years started using an updated engine called the N63TU.

A new timing chain replacement kit is only a few hundred dollars but getting it installed is pretty labor intensive and can run you several thousand dollars for the entire repair.

If the timing chain broke and caused lots of engine damage, your only options are to rebuild or replacing the engine altogether.

9. Transmission Issues

The second generation BMW M6’s SMG semi-automatic transmission is notorious for being very high maintenance.

It’s the same transmission found in the M3 and M5 from the same era, and the same issues affected these models.

The most common problem is a faulty hydraulic SMG pump which costs around $800 for the OEM part.

These pumps are known to fail every few years so you’ll have to budget for a replacement and the repair in advance.

Unfortunately, most M6s were sold with the SMG transmission and manual models are not only significantly rarer but also more expensive in the used market. 

10. Worn Control Arms and Bushings

The 6-Series’ front control arms and oil filled bushings will eventually give out at around 50,000 miles and affect the car’s NVH (noise, vibration and harshness).

It tends to wear out quicker on the 6-Series because it’s a fairly big and heavy vehicle.

The bushings are filled with oil to reduce harshness of the ride but this also means it will start to leak when they wear out.

Symptoms of worn control arms and bushings include:

• Creaking or squeaking sound from suspension
• Increased vibration
• Vague steering
• Uneven tire wear 

Here’s how a few owners described their issues on 6Post.com:

“I’m getting a creaking from the front suspension. I’m hearing it over bumps and when turning at slow speeds say under 20mph. The creaking is more annoying than anything else. Steering seems a little vague offcentre but I’m not sure if this is in my head.”

“I had this in my m6. Everyone told me its my lower control arms. i bought a set, and the sound went away..it comes back when it rains.”

“I’m experiencing the same in addition to slight front end vibration. Prognosis is tension/strut arms. Got it on the lift and concluded that’s the culprit. Can’t wait to fix it. I just got my F06 GC and the vibration has been making it hard for me to love the car. I’m still getting used to the heavy, floaty feeling, but if that doesn’t get better I’m going full coilovers.”

A new set of OEM control arms and bushings typically costs around $500 for the parts alone.

Installing the new suspension components should be fairly easy for any experienced mechanic and you’ll also have to get an alignment after the work has been done.

11. Tight Rear Seats

If you are planning on hauling passengers in the back then the 6-series may not be the wisest choice.

The rear seats are cramped and the rear seating area is tight.

Unfortunately, this is common for many four-seater convertibles.

Related: 11 Most Common BMW 5-Series Problems (Explained)

BMW 6-Series Pros & Cons

Pros

• Refined and luxurious interior
• Powerful engine options
• Sporty handling 
• Excellent ride comfort
• Lots of cutting edge tech
• Packed with features and creature comforts
• Large trunk for a 2-door
• Available all-wheel drive

Cons

• Cramped rear seats
• Reliability concerns for V8 engines
• Poor resale 
• Expensive maintenance costs

What Do The Reviews Say?

“Of course, there are sportier and smaller four-seat convertibles, and there are significantly more expensive ones too. But few can match the BMW 6 Series’ blend of style, quality and comfort. Drivers will find both engine options satisfying, while available all-wheel drive allows four-season practicality.”

“The 2018 BMW 6 Series prioritizes comfort over sporty handling. Nevertheless, most drivers will enjoy the driving experience. The 6 Series rides comfortably over bumps, and there’s plenty of power from both engine choices.”

“Premium leather and attractive plastics adorn the 6 Series’ interior. Operating most controls makes immediate sense, though the shifter takes a little getting used to. The convertible roof limits rear visibility, but that’s a problem easily solved by putting the top down.”

BMW’s iDrive infotainment system is very useful once you learn it, and optional gizmos such as night vision easily impress. Still, we’re disappointed that only Apple CarPlay is supported and not standard equipment.

2018 BMW 6-Series | Edmunds

What’s the Resale Value of a BMW 6-Series?

Here’s a quick look at used car pricing for the 6-Series on Edmunds at the time of writing.