WHAT IS CAN BUS? A FLEET MANAGEMENT GUIDE

Most people first encounter CAN bus when they begin exploring how modern vehicles exchange information between electronic systems. For fleet operators and telematics service providers, CAN bus becomes especially relevant when they need remote access to more vehicle data than standard GPS tracking can provide.

At first glance, CAN bus may seem like a highly technical topic filled with communication protocols, data formats and manufacturer-specific terminology. In reality, its purpose is straightforward: it allows a vehicle's electronic systems to exchange information and, with the right telematics hardware, makes valuable vehicle data available for fleet management applications.

The good news is that accessing CAN data is often much simpler than many service providers expect. Teams that already install wired GPS trackers are usually much closer to CAN-based fleet management than they realise. With modern telematics solutions, vehicle data can often be obtained through a familiar installation process with only minimal additional effort.

In this article, we explain what CAN bus is, how it works, what types of data it provides and why it has become an important source of information for fleet management solutions.

WHAT IS CAN BUS? 

CAN bus (Controller Area Network) is a communication system that allows a vehicle's electronic components to exchange information with each other. Instead of requiring a separate wire for every sensor and control unit, it enables multiple systems to share a common communication network.

Virtually every modern vehicle relies on CAN bus, including passenger cars, vans, trucks, buses and electric vehicles. Through this network, systems such as the engine, transmission, braking system, dashboard and many other components continuously exchange information.

For fleet management, CAN bus serves as a gateway to valuable vehicle data. Depending on the vehicle, it can provide access to parameters such as fuel consumption, fuel level, engine speed, mileage, engine temperature, door status and many other operational metrics.

HOW CAN BUS WORKS? 

Every major vehicle system is controlled by its own electronic control unit (ECU). Examples include the engine, transmission, anti-lock braking system, airbags and climate control. Modern vehicles can contain dozens of ECUs and, in some cases, up to 150 electronic control units, each responsible for a specific function.

BENEFITS OF CAN BUS 

Before CAN bus, vehicles relied on point-to-point wiring: every sensor, switch, and control unit needed its own dedicated wire running back to wherever that signal was used. As vehicles added more electronics over the decades, wiring complexity increased significantly.

CAN bus replaced most of that point-to-point wiring with a single shared network, providing several important benefits:

Reduced wiring and weight. Using a shared network reduces the amount of cabling required throughout the vehicle, helping manufacturers reduce vehicle weight and wiring costs.

Real-time communication. The network prioritises urgent messages, allowing safety-critical systems and operational functions to communicate quickly and reliably.

Fault tolerance. CAN bus is designed to operate reliably in demanding vehicle environments. It also helps prevent a single malfunctioning device from disrupting the entire network.

Standardised diagnostics. The same communication infrastructure supports diagnostic systems such as OBD-II, allowing technicians to access vehicle information for troubleshooting and maintenance.

These advantages are a major reason why CAN bus became the standard communication protocol used in modern vehicles.

CAN BUS, J1939 AND FMS IN HEAVY-DUTY VEHICLES 

In trucks, buses and other heavy-duty vehicles, CAN data is commonly organised using SAE J1939, a communication protocol built on top of CAN bus.

J1939 defines how vehicle data is structured and exchanged between systems. Information is grouped into Parameter Group Numbers (PGNs), while individual values are identified using Suspect Parameter Numbers (SPNs).

Because many commercial vehicle manufacturers follow the J1939 standard, telematics providers can often access a consistent set of parameters across multiple makes and models. On many European trucks and buses, this is complemented by FMS (Fleet Management System), a standard developed by manufacturers such as Daimler, Volvo, Scania, MAN, DAF and Iveco. FMS is built on J1939 and defines a common set of data, including speed, engine RPM, fuel level and total distance, that is made available through a dedicated interface. This gives telematics devices a manufacturer-approved way to read key data without connecting to the internal vehicle network.

However, neither J1939 nor FMS covers every available parameter. Depending on the vehicle and manufacturer, additional OEM-specific interpretations may be required to access a broader set of vehicle data.

CAN DATA AND OBD-II IN PASSENGER CARS AND LIGHT COMMERCIAL VEHICLES 

Passenger cars and light commercial vehicles often follow a different approach. Although CAN bus remains the underlying communication network, manufacturers typically define their own data structures and parameter mappings. As a result, available vehicle information may vary considerably between brands and models.

Many people assume that OBD-II and CAN bus are the same thing, but they serve different purposes:

• CAN bus is the vehicle's internal communication network

• OBD-II is a diagnostic interface that provides access to selected vehicle information

A useful way to think about it is that CAN bus is the language spoken inside the vehicle, while OBD-II is one of the available access points.

For telematics solutions that require more than basic diagnostic information, manufacturer-specific CAN interpretations are often needed to unlock a wider range of available vehicle data.

THE VALUE OF CAN VEHICLE DATA IN FLEET MANAGEMENT 

GPS tracking tells fleet operators where vehicles are and how they move. CAN data adds visibility into what is happening inside the vehicle by providing access to operational parameters such as fuel consumed, engine performance, vehicle utilisation and maintenance-related information.

For many fleets, fuel monitoring is the first step into CAN-based fleet management because it addresses one of the largest operating costs while demonstrating the practical value of vehicle data.

FUEL MONITORING WITH CAN BUS 

For many fleets, fuel ranks among the main largest operating expenses, can be actively reduced through better visibility and driver behaviour improvements. According to the U.S. Department of Energy, telematics and fleet-management practices can help organisations reduce fuel consumption by up to 10%.

The importance of fuel efficiency has become even more apparent as diesel and petrol prices continue to rise globally. As fuel expenditure grows, fleet operators increasingly seek solutions that provide greater visibility into fuel usage, consumption patterns and potential losses.

Based on data acquired from GlobalPetrolPrices.com on 17 September 2026.

It is therefore not surprising that fuel monitoring is often the first requirement that extends beyond basic GPS tracking. When customers look for fuel visibility, telematics service providers frequently consider fuel level sensors (FLS). These sensors can be highly effective, particularly when the primary objective is fuel-level monitoring and fuel-theft detection.

However, fuel-level sensor projects often require additional hardware, calibration procedures and specialised installation work. In some cases, fuel tank drilling may also be necessary. As deployment complexity increases, scaling the solution across larger fleets can become more time-consuming and costly.

For fuel-consumption and efficiency monitoring, CAN data often provides a simpler alternative. A telematics device capable of reading CAN data can access fuel-related information directly from the vehicle, including:

• Fuel level

• Fuel consumed

• Instant fuel economy

• Remaining driving range

• Mileage information

By accessing fuel data directly from the vehicle, fleets can often begin monitoring fuel usage without introducing an additional hardware layer. Equally important, the same CAN connection can provide access to much more than fuel information alone, allowing telematics service providers to upsell additional fleet-management services without requiring another installation project.

To help you learn more about Teltonika’s fuel monitoring solutions, we prepared an article Fuel Control: What Solution to choose?

CAN DATA BEYOND FUEL INSIGHTS 

Fuel monitoring is often the initial reason fleets explore CAN data, but it is rarely the only value they ultimately gain. Once a telematics device is connected to the vehicle's CAN network, the same installation can provide access to a broader range of operational parameters. This enables solutions that support maintenance planning, driver behaviour analysis, vehicle utilisation reporting and security monitoring.

For example, parameters such as engine temperature, mileage, engine hours, service indicators and other maintenance-related data can help identify developing issues before they become costly breakdowns. An increase in engine temperature, for instance, may indicate a cooling-system problem that can be addressed during scheduled maintenance rather than after a roadside failure. 

What starts as a fuel-monitoring project can therefore become a foundation for broader fleet-management capabilities without requiring additional hardware installations.

MORE VALUE FOR FLEETS – MORE OPPORTUNITIES FOR TELEMATICS SERVICE PROVIDERS 

For telematics service providers, CAN data is more than just an additional source of vehicle information. It enables the transition from basic GPS tracking to higher-value fleet-management services that address fuel costs, driver behaviour, maintenance and vehicle productivity.

For fleet operators, this means lower operating costs and better business outcomes. For telematics service providers, it means stronger customer retention, increased recurring revenue and greater earning potential from every connected vehicle.

THE PRACTICAL WAY TO START WITH CAN DATA 

Many telematics service providers hesitate to start CAN projects because they assume that every vehicle requires custom engineering, protocol expertise and extensive CAN knowledge.

In reality, accessing CAN data with FMC150 is often much simpler than expected. For installers already familiar with wired telematics devices, the starting point remains largely unchanged. Standard connections such as power, ignition, iButton, and relay control for immobiliser scenarios are installed the same way as with other telematics projects.

Note: the availability of parameters depends on the vehicle model, manufacturing year, and powertrain type. 

The only additional step required, compared to basic wired GPS tracker, is connecting FMC150 to the vehicle's CAN network using the vehicle-specific installation guide provided by Teltonika.

With FMC150, installers do not need to become CAN engineers. The device supports CAN data acquisition across 2,200+ vehicle models and, in total, provides access to 100+ CAN parameters. Instead of manually identifying and mapping available vehicle data, telematics service providers can rely on existing vehicle support and focus on delivering fleet-management solutions.

CAN BUS FOR EVS 

CAN bus is not limited to vehicles powered by internal combustion engines. Electric vehicles also rely on the CAN network to exchange information between the battery management system, electric motor and other vehicle systems.

FMC150 extends CAN data acquisition to electric mobility projects by supporting 150+ EV models, making parameters such as battery state of charge, charging status, battery temperature, remaining range and other EV-related data available for fleet management.

This allows fleet operators and telematics service providers to monitor both conventional and electric vehicles using the same telematics device.

READY TO SEE FMC150 IN ACTION? 

If you are ready to start your first proof of concept, contact your Teltonika sales manager or reach out to us via the contact form.

Looking for more details? We have prepared a guide – "Grow beyond tracking with FMC150", where you can get more details about:

• Simpler installation with easily accessible CAN bus connection points

• Tool that helps accelerate large-scale fleet deployments

• Accessory which makes FMC150 installation even more straightforward

• Fleet management platforms already supporting FMC150 and CAN data

FAQ 

What is CAN bus used for?

CAN bus is used to let a vehicle's electronic systems — engine, brakes, transmission, and more — communicate with each other and share data, without needing a central onboard computer to manage it.

Is CAN bus the same as OBD-II?

No. CAN bus is the underlying network; OBD-II is a standardised port that gives access to some of the data traveling across that network. Not all CAN data is exposed through OBD-II.

What tools do you need to read CAN bus data?

At minimum, a CAN bus interface – either a dedicated data logger or a telematics device with built-in CAN support – plus fleet management platform to display the data it captures.

How is CAN bus different from a GPS tracker?

A standard GPS tracking solution already provides a wide range of fleet management capabilities, including vehicle location, trip and route history, driver identification, geofencing, event monitoring, and support for various accessories and external sensors.

CAN-enabled tracking extends fleet visibility with parameters such as fuel level, fuel consumed, mileage and engine RPM for ICE vehicles, alongside battery state of charge, remaining range, and electric motor temperature for EVs, as well as other operational information available directly from the vehicle system.