Condition Based Service

CBS (condition based service); is a service system developed by BMW to have a vehicle decide for itself when service is due. This post will go through how the system works and what and how a vehicle decides services.

The CBS data is different from car to car. For example, an M vehicle will have more items serviceable than a non M car. All this data is stored in the vehicle and can be viewed to give you a basic idea of what’s due. This is only a basic view and does not show all of the included services. More on this later.

The best way to see your CBS data is to have your key read out at the local dealer. How this works is the vehicle’s key will store data from the car about service and mileage. The print-out from the key reader program will show remaining time and mileage for the services. If the service is due, it will put a X next to the service and say “recommend”.

Photo credit: Google

The vehicle decides what is due through different methods. For instance, the brake fluid is time passed only. Every two years the fluid needs to be changed. If you have a new vehicle the first brake fluid service is three years, then it changes to every two years after that. The brakes are calculated out using brake pressure and brake usage. As this mileage counts down, the brake sensors are backup for if the pads wear faster than the calculation. If the sensor is cut, then the service light will turn on. In some of the older models BMW used a two stage brake sensor. When the first loop of the sensor was cut, the CBS data would use this information for adjustment of the brake wear calculation until the last loop is cut.

The oil change is calculated by several items such as oil temp, engine run time, outside air temp, fuel quality. Most new BMWs are on 10,000 mile or one year oil change interval. Some older models are on 15,000 mile, two year oil change interval. This mileage can change on how the car is driven. Let’s say you do weekend track events and push the car through its paces. The mileage for when the oil service is due could change to account for the oil break down.

The included services mentioned are linked to main services. For instance; the oil change can have micro filter, spark plugs, air filter and vehicle check linked. Meaning, when a oil change is due, these other service items could be due as well. The same happens in some older BMWs with brake fluid and micro filter being linked together. Later on, BMW put a micro filter with oil to be changed more often. On M models, some other services are linked with oil change such as: rear diff and possible transmission depending on model and year of the vehicle. Diesel engines will also have a fuel filter service linked to engine oil.
If you look at the picture of a key read above you can see a column called “Service Counter”. This is how many times that service has been done to the vehicle. This feature is how these inclusive items are decided if they are due. For example, spark plugs that are linked to oil service on some models are due every three oil services. This is where the service counter comes into play…for when that service would be due.

I know this seems like German engineers are reinventing the wheel in a confusing way. The main reason deduced is likely to save money on maintenance costs during the warranty period. Once this concept is understood, it can make maintaining your BMW much easier!

Signs of a failing transfer case

A transfer case is a device that splits the output of the transmission for the front and rear wheels. To give the vehicle four wheel drive or all wheel drive depending on how the vehicle uses it. BMW uses a few different transfer cases through out its all wheel drive vehicles. The main transfer case design we will be talking about is x drive.

Photo credit to Google Images

The older transfer cases were not as problematic as the newer ones, mainly because they are very simple units compared to recent models. The older units were either chain drive or gear to gear driven. As long and the fluid was changed at the appropriate intervals then the chances of having issues was quite small. These type of units were in the e46, e83, e53, e30. Some of the life cycle impulse (LCI) of those models did get a x drive transfer case during the update.

The x drive transfer case was developed for one main reason, saving fuel economy. The transfer case uses a wet clutch to be able to split the power and the vehicle needs it for the front wheels. Under normal driving conditions, in a straight line with no wheel slippage, most of the power is sent to the rear wheels. Once the car senses wheel slip it will send power to the front wheels and do a 50/50 split between front and rear. The wet clutch is activated by electric motor and ball and ramp system. The early x drive transfer cases had control module separate from the electric motor. In newer models, the module and electric motor are all together.

The transfer case can fail and in most cases does without any warning lights. Normal sign of failure is a shudder when taking tight turn either direction. This is a sign of the wet clutch being stuck engaged. This occurs because; normally when turning the transfer case will disengage the wet clutch to allow the front and rear wheels to turn at different rates. Another common sign of failure is a drivetrain vibration when accelerating. I have even seen a complete internal failure where the transfer case would no longer drive the rear wheels, just the front. The easiest way to diagnose; if the transfer case is the issue is to unplug the electric motor and drive the car. If the issues go away or change, most likely the transfer case is the issue and should be replaced. In my experience, replacing just the electric motor does not solve the issue. When you replace the transfer case with a new motor because of the module it will need to be programmed.

Photo credit to Google Images

The best way I have experienced to avoid a transfer case failure is to do proper maintenance. BMW’s system for when to service the transfer case is flawed. Your vehicles transfer case module will set a fault code when a service is due. Problem is this fault does not set a warning light or message. The only way to see if it is set is to do a fault memory read out. Many people never know when to change the fluid on the unit. And by the time they find out it’s too late and the damage is done. I recommend doing a fluid change every 40-50k miles. The early models were easy and had a drain and fill plug. Drain fluid out and fill until fluid spills out, very simple task. For engineering reason unexplained, the new transfer cases don’t have a drain plug. BMW states you need to remove the transfer case and tip it on its side to get the fluid out. I have found in the field to use a suction pump that has a small enough hose to suck the old fluid out and fill with new fluid work just as well. Starting with the G12 the latest transfer case will need software to open up and plunger and chamber system to get all the fluid out. The reason for this new system was to improve fuel economy again.

I hope after reading this you can diagnosis potential issues with your transfer case. Secondly, be able to prevent any issues with your transfer case for many years to come.

N63 oil pump whine

This is a PSA to N63 owners about a noise that can be hard to catch on the N63, and could be detrimental to your engine. As if the N63 didn’t have enough issues already!

I have seen this issue only a handful of times, but only on the N63 not the TU versions. The noise can show up differently as well. I have had it only at idle when there is a whining noise that sounds like its coming from the passenger side dash. Also, had a loud whining noise when at 1200 to 2500 rpm. To isolate the noise, you can hear it best on the engine oil cooler lines using a stethoscope.

As mentioned before, I have only seen a handful of these pumps come in making a noise. After reading the forums I have found many other N63 owners are having the same issue. The oil pump is a very important part of the engine and is worrisome if it is making noise for engine health. If the oil pump fails, the pump will not supply oil to the motor important moving components and will cause major damage and eventually engine failure.

The pump is easy to replace, which is surprising since most things on the N63 are not easy. You just remove the lower oil pan and can access the pump. Remove the 3 bolts securing the pump sprocket. Release the bolts holding the pump and remove the pump. Replace the pump seals and reinstall in reverse. Check the oil pump chain tension. Do clean the threaded holes for the lower oil pan using a tap. These are not exact instructions just representation on how easy the repair is. You should always check repair instructions before doing the repair.

BSD faults after using aftermarket parts:

This is a issue I see a lot when people are using aftermarket parts to save money. I am not going to preach about having to use OEM parts only. In this post, I would just like to explain why some of these parts will cause faults and how to avoid it. With this knowledge you might even save a few dollars!

Picture from

The two most common components I see issues with are: alternators and electric water pumps. BMW uses a single wire bus system called BSD (bit serial data). This is a bus system that the DME (digital motor electronics) uses to communicate with alternator, water pump, IBS (intelligent battery sensor) and oil condition sensor. The DME receives information from all these components and also can send commands to the alternator and water pump. Let’s start first with the alternator: the DME gets information about voltage level and battery charge rate and makes decision on how the alternator operates and charges. By doing it this way the vehicle only charges how much and when needed. This saves engine drag and fuel economy. The same happens with the water pump. The DME makes a calculation on water pump speed according to many engine sensors, temps and modes of operation; such as sport mode engaged or high driving. Again, this is done to save on engine drag and fuel economy.

All these components on the BSD network have a computer processor in them in order to send and receive messages on the BSD network. A lot of the super cheap water pumps and alternators that are out there do not have this processor on them and thus can not communicate on the network. Some can even bring the whole network down and cause some problems…but I will get into that in a minute. The aftermarket parts will work, don’t get me wrong, other wise companies wouldn’t sell them. But they don’t work the same as BMW designed ones. So for instance lets say you replace the alternator with OE rebuilt one from aftermarket reseller. Yes, it will look the same and probably be rebuilt with parts from which ever alternator you have Valeo or Bosch. The OEM regulators have a computer processor. A processor will not be in the rebuilt version in order to offer a much cheaper part to consumers. This after market alternator will still work with your car and it’s quite clever. When the BSD communication fails on the car, the alternator fail safe will charge at 14.5v constantly. The aftermarket alternator will still charge, but will not be able to vary the charge level or recharge well if the battery is depleted (such as cold weather). This same principal is used for the water pump. Keeping it a constant flow rate to keep the engine from overheating.

Here are some issues I have seen from the aftermarket components: when plugged into the BSD network it can actually cause a short circuit in the network and bring the whole network down. The components on the network can no longer function properly when the network is compromised. In this scenario, I have seen a car randomly overheat and some have charge malfunction lights come on even when charging properly. The BSD fault codes will not cause any malfunction lights and can only be read out with BMW specific software. The worse case scenario is when that aftermarket component can cause damage to the DME. This case is very expensive and very rare, but I have seen it happen.

I cannot tell you to not use aftermarket parts, but just use reputable brands. Do your research on that component to make sure it works fully with your car. If something is too good of a deal to be true then there is a reason why.

Alpina B6 lack of power

Recently, I encountered a weird issue with a B6 where it lacked power. If you drive the car around town, typically you won’t feel a lack of power. If you decide to do some spirited driving, around 80 mph, the car will fall flat on it’s face. Lights do not come on or faults stored for the lack of power.

I replaced mass airflow sensors, but they didn’t help the issue. Then I decided to check into the high pressure fuel pump. They all had correct pressure under high load. Next, I investigated the lower pressure fuel pump and it had the correct pressure under high load, (around 5.5bar of pressure). Finally, I checked all coolant pumps since the issue seemed to get worse the hotter the engine or air temperature got. It was discovered that the inter cooler pump was not pumping properly. What was needed was to remove and replaced the pump. Alpina their own proprietary pump. In the end, I replaced the pump and bleed the system. During the test drive, it was concluded that the power was functional.

The Alpina uses a modified N63 engine to create the extra power it is known for. This issue would transfer over to any N63 or S63 since they use the same system setup. Make sure if you’re having a lack of power with no faults or warning lights on that you check into the operation of the inter cooler pump.

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Aftermarket parts and your warranty

This is a common question I get from people that want to modify their BMW. Short answer is it can affect your warranty, but not in the manner you may think.

There are many modifications you can do to your vehicle these days some with physical parts and some with software. Any aftermarket parts does not automatically kill your vehicles warranty as most would believe. Only the parts you changed would be considered not covered under the original BMW warranty. In addition, if that aftermarket part causes damage to any other part on the vehicle, then that will also not be covered under the warranty. For example, if you replace your oil cooler thermostat with a different temp rating one and it gets stuck closed and damages the engine; the engine would not be covered from this. This ,of course, is an extreme example.

The most popular modification to any BMW is tuning the engine for more power. Two main ways I see this done, one is flashing the DME (engine control unit) or using a device called a piggy back. When you flash the DME you are installing a modified engine parameters map. BMW has recently started cracking down on people doing this modification. Every time a BMW technician reads out fault memory with factory equipment a data package of the vehicle called FASTA data is sent to BMW. BMW has a team of people who spend all day going through this data to find cars that have been tuned. Once they find a car that has been tuned they will flag the VIN and stop the DME and power train warranty on the vehicle. This basically means your DME and engine are no longer covered under the OEM warranty for any repairs. The rear differential and transmission repairs needed are up to BMW decide if they will cover under the OEM warranty. This is all done automatically by BMW, the dealer personally has no control over this.
Flashing the DME, in my opinion, is the easiest and best option for tuning a BMW.

A piggy back system modifies signals from the engine to the DME to create more power. A lot of tuners use this system because it is basically electronically untraceable beside the physical components installed on the vehicle. In my opinion, since this system uses a physical component more issues can arise from this type of system. I have first hand seen weird fault codes occur and two complete DME failures from this type of system. In a world where BMW is looking for any modifications on the vehicle this system can be left on the car while sending FASTA data since the DME will never sense the modification.

So if you are planning on modifying your BMW, please be aware of the risks involved with what type of mod you are doing. The easiest ones are exhaust, air box, suspension and wheels. Those modifications normally don’t cause any issues. The engine tuning is by far the most risky to do since BMW is looking for it and safety parameters built into the DME software. Don’t worry much about modifying your BMW since if you’re reading this you have already considered it. In summary, just be aware.

Winter blues

Hello all,

It’s that time of year again, when the leaves start changing and soon…we know the frigid winter will be upon us. With that said, it’s time to put that BMW away for storage, sadly, until next driving season. It makes me question living in the Midwest. Here are some ideas you should implement when you store your vehicle for the winter:

1. Wash the vehicle’s exterior and give it a good coat of wax. Wax is (for those who aren’t familiar) a protective barrier for your paint. Don’t forget to give the leather a nice leather conditioner as to keep the leather from drying out.

2. It is never a bad idea to have a car cover as well, it can be quite helpful.

3. Fill the tank with fresh fuel and add stable to the gas tank. Sta-bil helps the fuels from going bad on you faster.

4. Depending on where you store your vehicle, there are two different options for battery care. The vehicle’s battery needs to be charged while in storage either with a trickle charger in car or out of car with a normal charger. If you do use a battery tender/ trickle charger, make sure it has a smart chip to monitor battery voltage and switch itself off when charged. If not, it could ruin your battery – beware!

5. If the vehicle is stored in a colder climate, you will need to check the coolant freezing point to make sure it will stand up to your average winter temps. If this step is skipped – you will have major repairs in spring. (note wind chill does not affect cars so don’t take that into account)

6.(Optional) Change the vehicles oil before placing it in storage. Why? Dirty oil has a higher acid value and will break down the oils cleaning and protection abilities.

7. (If stored for a year or longer) Leave the vehicle resting on jack stands to prevent flat spotting of the tires. You can also look into tire stands that will prevent flat spotting.

8. You need to take preventative measures to keep unwanted guests out of your vehicle. Cover tail pipes with socks and put moth balls down. Different parts of the country will have different guests.

9. Fill tire above specs. Now, don’t go crazy with this just a little bit, no more than 10 psi over.

Note- You may have heard about putting WD-40 or oil on the rotors to keep them from rusting. I don’t believe this is the best idea. The pads can not get oil on them or it will ruin them.

That was the basics on what you need to know about vehicle storage. Here are some tips about restart in the spring.

1. Remove car cover and check under car. Look under the hood and tail pipes for unwanted guests.

2. Check for any leaks and fluid fill levels. Remember to reinstall the battery if removed (make sure battery is fully charged a full battery will measure 12.6v at 12v your battery is low on charge)

3. Turn to the key to the on position, but DO NOT START. Make sure you hear the fuel pump prime and observe for any fuel leaks. If no leaks are found, turn the key off and then back to on position a couple times to make sure the vehicle’s fuel system in primed.

4. (Optional) You can removed the fuel pump fuse before doing step 3 above and crank the engine over to prime the oil system of the engine …if you are worried about dry starts.

5. Start the vehicle and listen for any weird noises (note the engine will make some extra noise on start up after sitting for months). DO NOT step on the accelerator! Allow the vehicle to warm up to full operating temp. (note do not do this in a inclosed area make sure the garage door is open because of fumes) Look for any leaks, the tail pipe will have a lot of water emitting from them this is normal. While warming up, take some time to adjust tire pressures.

6. Go ahead and drive the car! It may stick little from the brakes, but just give it some gas and it should start moving. Immediate spirited driving is not recommended, because your brakes adjust. Drive moderately and use the brakes the same until they feel normal to you again. Plus side, this will give any time for the flat spots on the tires to go away as well.

After all of your hard work you are ready to be back on the road. Have fun!

The oil leak that keeps leaking

A frustrating problem that has even plagued seasoned BMW technicians. You replace a valve cover gasket for a leak and the vehicle will come back still leaking. Even worse, not the only engine that has this issue. In this post I will focus on the most common engines the N62, N54, N52, N20.

N54 is the one we see the most in terms of having an oil leak from the plastic cover cracking. The best way to tell if your cover is leaking is to look for oil stains in the valley by the injectors and ignition coils. The cover cracks, typically right below the crankcase vent cyclones.

See the oil trace running down the valley a sign of a crack.
You can see a hair line crack

Above, you can see there is a hair line crack in the cover causing this leak. Normally, no fault codes or drivability concerns are found when this occurs. The crack is hard to see, so best way to find any crack is a smoke machine. I understand the average person doesn’t have access to a smoke machine. A good inspection for the oil traces are the next best thing.

The N20, though not as common as the N54, still have a lot of them. Normally, plastic cover cracks in the back rear corner of the cover towards the exhaust manifold. This one is a hair line crack that is extremely hard to find, smoke is still the best option. Watching oil trails is another way to find a leak, but can be difficult and small to follow.

The N52 cover is a different leak most of the time. They can still crack, but most of the time what leaks is the oil separator control valve. Normal signs of this can be oil staining around the valve and in the last two ignition coil valleys. It is normal to find oil leaking from the valvetronic motor seal and eccentric shaft seal. At times, right below the valvetronic motor there will be a large pool of oil from a leaking seal. Those are not a valve cover crack issues, just the aged seals.

Circled is the vent valve that can leak.

The N62 normally doesn’t crack on its own. I find most of the time when the cover is cracked its because someone installed the cover wrong. Don’t get me wrong, those N62 covers are a pain to install and can be easily damaged. The common repair of upper timing cover gasket is usually when we see a return car with oil leaking from the cylinder head cover. This is because it was installed incorrectly and cracked. Normally, you will find the crack towards the bottom of the valve cover close to the exhaust. The cover has 3 guides on them and if not seated correctly against the cylinder head; when you tighten down the cover it will damage and cause the leaks.

The three guides on the bottom of the cover.

Hopefully this points out some common issues, saving you from replacing a gasket and still having an oil leak.

The DIY resource page

As these cars get more advanced, they in turn become more complicated and harder to repair. This on-going post is to help point DIYers to the best tools for their BMW projects.

BMW parts catalog
I prefer using, since it is BMW’s parts catalog online. The site can help with parts numbers and part super sessions.

BMW repair info and electrical diagrams
This site has all the oem wiring and repair info, just as the BMW techs do.

BMW repair shop
Did you just move and are not sure where you need to take your BMW? Start here.

BMW Paint codes
All paint codes since 1960 to the present