BMW E39 Insights: Rediscover your BMW with the right diagnostic device


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Are you a proud owner of a BMW E39 and have the desire to learn more about the details and specific features of your vehicle? Want to minimize expensive garage visits and customize your car? The Carly diagnostic device could be your solution.

BMW E39: A look back at a legend

The BMW E39 marks a remarkable era in the history of the Bavarian automaker BMW. This generation of the 5 Series, produced from 1995 to 2003, followed the E34 and set new standards in design, technology and performance. The E39 was a step forward in BMW’s commitment to ride comfort and driving dynamics, and to this day it has secured a place in the hearts of many car enthusiasts.


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The model types of the BMW E39

The E39 series offered a wide range of models to meet the needs of different drivers. It began with the basic 520i and extended to the impressive M5.

  • 520i and 523i: These models, powered by an inline six-cylinder engine, offered a balanced mix of performance and efficiency.
  • 525i, 530i and 535i: These models offered higher engine power, with the 535i having a V8 engine.
  • 540i: This model, powered by a 4.4-liter V8 engine, offered near sports car-like performance.
  • M5: The M5 was the pinnacle of the E39 model line and is still considered by many to be the best sporty saloon ever built. It featured a 4.9 liter V8 engine that delivered 400 horsepower.
  • Diesel variants: The 520d, 525d, 530d and 535d models offered fuel-efficient diesel options.
  • Touring: The BMW E39 was also available as an estate version (Touring), which combined the luxury and performance of the Saloon with additional space and flexibility.

Special features of the BMW E39

The BMW E39 was full of innovations and technological advances. Some of the most notable features are:

  • Design: With its angular yet elegant design, the E39 set standards in terms of aesthetics. It was also the first model to introduce the now signature “Angel Eyes” front lighting.
  • Technology: The E39 was one of the first vehicles to be equipped with BMW’s iDrive infotainment system. It also offered a range of driver assistance systems, including Park Distance Control and the Professional navigation system.
  • Driving dynamics: BMW is known for its driver-oriented cars and the E39 was no exception. With a perfect 50/50 weight distribution, precise steering and powerful engines, the E39 offered a driving experience that is still hard to beat today.

The BMW E39 remains a legend in the automotive world. It symbolizes a time when luxury, technology and driving performance were perfectly matched. With its elegant design and unmistakable road presence, the E39 was a true style icon of its time. Its advanced technical features set new standards in safety and comfort, while the powerful engines ensured impressive performance on the road. The impeccable combination of performance, comfort and technology made the BMW E39 a model that is still appreciated by automotive enthusiasts worldwide.


Diagnostic equipment basic knowledge

Before we introduce you to the perfect diagnostic tool for your BMW E39, we think it’s a good idea to give you an overview of the basics of vehicle diagnostics so that you can properly classify the importance of each component.

Types of diagnostic equipment

For a correct vehicle diagnosis it is indispensable to have the right diagnostic device. There are three different types on the market: standalone external devices, software for laptops, and apps for smartphones. Each of these types has its merits and weaknesses, but in our opinion, the smartphone app is the optimal solution, as it is both user-friendly and inexpensive.

External diagnostic devices usually have a small screen and are mainly suitable for basic diagnostics. Professional equipment for workshops can cost several thousand euros and is not easily transportable. Smaller, portable external devices may be less expensive, but offer limited features and small screens that only display error codes. The interpretation of the codes is then up to you. In addition, you need to carry this device with you at all times, which requires additional planning.

Software solutions for laptops are rather unsuitable for the average driver or car fan, as both the laptop and the corresponding adapter cable have to be transported. You will have to purchase the software yourself and it may not be updated regularly. Updates may be chargeable, increasing the overall cost in the long run. Nevertheless, laptop solutions offer comprehensive diagnostic functions.

Smartphone apps, on the other hand, are especially handy because you have your smartphone with you all the time. The apps are user-friendly, have a wide range of features, and are usually updated regularly and for free. Our top recommendation is the Carly app. In addition to comprehensive diagnostic functions, it offers a number of other features that we will discuss in more detail later in this article.

The BMW E39 error code

Understanding the diagnostic system of vehicles, especially the BMW E39, is essential to correctly interpret the technical requirements and possible problems. Every vehicle is equipped with a variety of control units that monitor different systems and functions. In the event of deviations from normal operating parameters, these control units generate error codes, also known as DTCs (Data Trouble Codes).

An extensive repertoire of error codes exists, and these are basically divided into two categories: universal standard codes and manufacturer-specific codes. While most diagnostic devices are capable of reading general fault codes, you’ll need special devices or apps to decipher manufacturer-specific codes, which are especially relevant for models like the BMW E39.

The structure of an error code is always the same and consists of five characters. The first character identifies the affected area: B stands for the body, C for the chassis, P for the powertrain (engine and transmission), and U refers to the vehicle’s network system. The second character indicates whether the error code is general (“1”) or manufacturer-specific (“2”). The third character (1-8) indicates the specific system that is affected. The last two characters describe the specific error.

Most diagnostic tools only display the error code, e.g. P0730 or U0126. Then it’s up to you to research the exact error and its possible solution. Sophisticated diagnostic tools additionally provide a description to the error code. The best apps, such as Carly, analyze the error code even further and prioritize the errors by urgency, which can be especially useful for BMW E39 owners .

BMW E39 control units

At the heart of every BMW E39 are numerous control units, each with a specific task, from air conditioning to engine monitoring. In total, there are dozens, if not hundreds, of these intelligent helpers installed in cars and connected to each other by a central communication network. This network represents the nerve cord of the vehicle and enables seamless communication and collaboration between the individual systems.

When an ECU detects a deviation from the specified parameters, it usually tries to fix the problem internally to keep the affected systems running smoothly. In such situations, an error code is generated, but it usually has little effect. Only in the event of major deviations that the control unit cannot correct internally is a warning message sent to the driver or a serious error code triggered. Apps like Carly can analyze these error codes and present the most important ones in a descending order, also providing an overview of the vehicle’s general condition.

BMW E39 OBD interfaces

For communication with external diagnostic devices, the BMW E39 has an OBD2 interface, which is usually located under the dashboard on the left side of the brake pedal. When using an OBD2 scanner, it is crucial to pay attention to quality to ensure accurate diagnosis and avoid possible damage to the control units. The scanner translates commands into a language that can be interpreted by the vehicle. With mobile solutions like the Carly app, a compatible OBD2 device like the Carly 20-pin adapter connects wirelessly to the smartphone or tablet, with Bluetooth or WLAN being the most common connection options. The scanner can be left in the OBD2 socket when not in use or conveniently stored in the glove box or other storage compartments.

BMW E39: Image from <a href=";utm_medium=referral&amp;utm_campaign=image&amp;utm_content=1838744">Pexels</a> on <a href=";utm_medium=referral&amp;utm_campaign=image&amp;utm_content=1838744">Pixabay</a>
BMW E39: Image from Pexels on Pixabay

A brief history of the OBD standard: A journey through time

The beginning: OBD-I

The history of the On-Board Diagnostic (OBD) system began in the late 1980s when the U.S. began to implement stricter emissions standards. As a result, in 1988, the State of California introduced regulation that required the OBD-I system to be installed in all newly produced vehicles. These systems allowed vehicle manufacturers and repair shops to access some specific engine and emissions system data to determine if the vehicle met the new standards.

OBD-II: Uniform standards

OBD-I represented a major advance, but was far from perfect. There was no universal standard, which meant that each manufacturer developed its own system. This inconsistency created major challenges for diagnostic tools and service centers. The solution came in 1996 with the introduction of the OBD-II standard in the U.S., which mandated a variety of uniform codes and diagnostic ports for all vehicles.

The globalization of OBD

OBD-II quickly became a global standard and is now mandatory in most countries, including Europe, Australia and Japan. It provides comprehensive fault coding, enabling detailed diagnosis of a wide range of vehicle systems. Today, OBD-II provides diagnostics for everything from engine and transmission performance to exhaust emissions and many other vehicle sensors.

OBD today: Technological advances

As vehicle technology has evolved and vehicles have become increasingly connected, OBD systems have also expanded their capabilities. Modern OBD systems provide access to a wealth of real-time data, ranging from engine speed and fuel consumption to advanced telematics data. They also enable access to proprietary manufacturer-specific data that was previously only accessible via special tooling and diagnostic systems.

In addition, the increasing prevalence of smartphones and wireless technologies such as Bluetooth is enabling the development of OBD adapters and apps . These make OBD data and functions accessible to every car driver and not just to professionals in workshops. They have made it possible for drivers to easily perform a variety of maintenance and diagnostic tasks themselves and better understand their vehicles.

The history of OBD is one of constant technological advancement and adaptation to new emission standards and vehicle technologies. Today it is an indispensable tool for anyone who wants to maintain, repair or simply better understand their vehicle.

Technology and innovation: The OBD story and the BMW E39

For all those fascinated by technical developments in the automotive sector, the story of how the on-board diagnostics (OBD) standard came into being is particularly illuminating. First launched in the U.S. more than four decades ago, OBD was developed to seamlessly monitor a vehicle’s emissions-related values. The underlying objective was to protect the environment: in the event of elevated exhaust gas levels, the driver was to be warned and thus prompted to take corrective action.

If you look at the BMW E39, you will find a vehicle that has taken a big step forward in the development and application of OBD. With its sophisticated ECU system, the E39 was able to effectively monitor a wide range of vehicle data and identify malfunctions at an early stage.

At the same time, it is exciting to see how the OBD standard continues to develop. Currently, for example, the OBD3 standard is being developed, which offers the possibility of reporting faults in the exhaust systems directly to the responsible authorities. Such a case would force the driver to make necessary repairs within a specified time frame to avoid penalties. However, whether and when this new standard will be introduced in Europe has not yet been conclusively clarified. But it shows how technology and regulation work together to improve vehicle performance and environmental protection. And the BMW E39, as an icon of automotive history, has made a significant contribution to this.

Understanding the technology: The CAN bus system in the BMW E39

Technology-savvy car enthusiasts will be delighted by the complexity and ingenuity of the so-called CAN bus system, which is responsible for the flow of data in the BMW E39. This system can be thought of as a kind of data highway on which information is sent back and forth between different points in the form of data packets.

Imagine changing a setting using the Carly app for your BMW E39. As soon as you change the setting, the app sends the corresponding command to the OBD2 adapter via Bluetooth Low Energy. This adapter then translates the command into a language that your BMW E39 understands and sends the information via the data bus to the corresponding control unit in your car.

The vehicle’s response then takes the form of a data packet, which in turn travels back to the interface via the data bus. From there, it is sent wirelessly to the app. All these steps happen in a fraction of a second, so you get almost immediate feedback about the successful change. The technology in the BMW E39 is an impressive example of how modern vehicles and digital technologies are seamlessly linked.

The art of vehicle diagnosis in the BMW E39

At the core of vehicle diagnostics is the recording and interpretation of fault codes. While simple and inexpensive diagnostic tools are only capable of displaying these codes, high-quality devices provide understandable text descriptions while also providing valuable information on how urgently a particular fault needs to be rectified.

The use of a powerful diagnostic device enables minor malfunctions and problems to be detected and rectified in good time. This helps avoid potentially costly repairs before they even occur. Especially with a technically demanding and complex vehicle like the BMW E39, such early diagnosis can be invaluable.

Investment in vehicle diagnostics for BMW E39

The costs associated with vehicle diagnostics consist of both the direct diagnostic costs and the potential savings from identifying and correcting faults at an early stage. A simple diagnosis in an automotive workshop can range from 25 to 60 euros, while the Carly app is already available for around 6 euros a month. In addition, the one-time purchase of the Carly Universal OBD scanner for 59.90 euros. A high-quality external adapter, such as the Carly scanner, is essential for any external diagnosis. With a suitable diagnostic device, several hundred to thousand euros in follow-up costs can be avoided each year.

The best choice for the diagnosis of your BMW E39?

Our goal is to make you understand that the Carly app is the optimal solution for your needs. It offers a wealth of additional functions, which we will discuss in more detail in a moment, and can be downloaded from the Apple App Store and the Google Play Store. The Carly app already has over one million downloads. Also, you can start with the free version of the app, which gives you access to a limited, yet impressive selection of features. Below we’ll give you an overview of the most important features of the Carly app.

BMW E39 diagnosis and condition assessment

The Carly app is not only capable of reading and interpreting generic fault codes, but also manufacturer-specific codes relevant to BMW and in particular the BMW E39. With the Carly BMW E39 diagnostic tool, you won’t be left in the dark, but will receive detailed explanations of the identified faults. But that is not all. Carly goes one step further and provides you with a condition assessment of your vehicle by ranking faults according to their urgency. This uses a traffic light system: If the indicator in your car is green, it is in good condition and no action is required. If the indicator is orange, you should consider further diagnostics as there are errors that should be fixed. With a red indicator, your car is showing serious problems that require immediate action.

The Smart Mechanic for the BMW E39

Carly ‘s Smart Mechanic feature answers the central question of every vehicle owner: “How serious is the problem and what action needs to be taken to resolve it?” The app gives you specific details on the severity of the problem and how to fix it, along with hands-on repair instructions written by experienced automotive technicians.

We combine the error data of your specific problem with our carefully curated database of repair tips and vehicle system descriptions. This way, you’ll get a deeper understanding of your car’s trouble codes and detailed repair tips. Carly OBD Scanner combines real-time data with extensive mechanical expertise and turns it into actionable advice you can use to improve your repair skills and do more repairs yourself.

Carly used car check: Avoid speedometer manipulation when buying a BMW E39

When buying a used BMW E39, the biggest challenge is finding a reliable vehicle. Speedometer tampering is a serious problem, and statistics show that up to one-third of used vehicles are affected. With the Carly used car check, you can minimize this risk. This unique feature checks all relevant ECUs and identifies signs of tachometer tampering. You will receive a detailed report that will help you assess the trustworthiness of the seller. With our BMW E39 diagnostic device you can save considerable sums of money!

Personalization: Optimize your BMW E39 with Carly

With the Carly app, you have the ability to not only diagnose your BMW E39 and check for trouble codes, but also make custom adjustments to a variety of vehicle functions. From adjustments to your headlights and turn signals, to comfort features, to your Park Distance Control (PDC) settings, power windows, and automatic climate control system – the possibilities are nearly endless.

Functions such as the welcome home lights, the automatic engine start-stop system and the electric tailgate can also be customized to your liking. With Carly you can make hundreds of different settings, test them out and change them again at any time.

In a conventional automotive workshop, individual adjustments can quickly become expensive – often the cost per adjustment is between €30 and €50. However, with the Carly app, you can make unlimited settings while trying out different options without fear of additional costs. Personalize your BMW E39 exactly as you want it and make it your very own!

Live data monitoring: Keep an eye on important parameters while driving your BMW E39

Carly’s live data monitoring feature gives you the ability to monitor much more than the basic information of your BMW E39. From specific values like boost pressure and battery voltage, to torque, air mass flow and many other parameters – you have the possibility to observe a wide range of vehicle data in real time.

Carly presents this data to you in a user-friendly and easy-to-understand way. You can tell at a glance if your BMW E39 is working properly or if there are any signs of problems. This gives you the opportunity to maximize your vehicle’s efficiency and performance by identifying potential problems early and resolving them before they can develop into major, costly repairs.

But that’s not all. With Carly’s live data monitoring, you can also gather important information about the condition of your engine while driving. You can keep an eye on the engine temperature to make sure your engine doesn’t overheat, or check the oil pressure to make sure the lubrication system is working properly. These features are especially useful if you’re going on long trips or traveling and want to be sure that your BMW E39 is always in top condition.

The Carly OBD scanner: the key to self-management of your BMW E39

With Carly, you have the ability to perform simple diagnostics, adjustments and service resets yourself. This saves both time and money. But, of course, there is always work that can be done only by professionals in a workshop. For these more complex problems, a professional assessment can be invaluable.

If you are a proud owner of a BMW E39 or plan to buy one, Carly is the optimal diagnostic tool for you. Features range from used car inspection to a variety of options to help you better understand and maintain your vehicle. But the real benefit is in the potential cost savings.

You’ll be able to do a lot of maintenance yourself and forgo a workshop visit whenever feasible. The financial advantages of the Carly OBD scanner become apparent after a short time, because numerous activities that would normally require expensive workshop visits can now be done by yourself. And it’s not just a question of money – saving time is also a key benefit.

Carly definitely exceeds your expectations and helps you save both time and money, while keeping your BMW E39 in the best possible shape and condition.

Image rights cover image: Image by Kasjan Farbisz on Pixabay

Keep in mind, that every car has different software and modules built-in. Therefore specific features will vary with every model.

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