# Periodical Vehicle Inspections with Smart Technology
## 1 Introduction
### OBD Reading  
OBD (On-Board Diagnostics) is an integrated self-diagnostics system incorporated within vehicles. The OBD-II socket, a 16-pin connector, is typically located near the driver's wheel, under the dashboard. The inception of OBD can be traced back to California, where the CARB (California Air Resources Board) implemented strict regulations and raised awareness regarding emissions control [24]. CARB mandated the use of OBD in all cars manufactured after 1991 to monitor and regulate the emission of harmful gases [25]. OBD-II plays a crucial role in the automotive industry by enabling the logging of various essential parameters of vehicles. It encompasses the analysis and diagnostics of small vehicle systems as well as facilitates comprehensive fleet management and route optimization [25].  
OBD-II (On-Board Diagnostics version 2) is a protocol used for identifying, diagnosing, and reporting the health and condition of a vehicle's engine to the user. It operates on the CAN (Controller Area Network) protocol, allowing the vehicle to connect with scanning tools and external hardware known as OBD scanners. These scanners can be connected to PCs or laptops to extract information from the vehicle's onboard computer, providing parameters such as driving speeds, engine speeds, coolant levels, coolant temperature, emission control, engine idle time, and other vital engine information [24].  
CAN is a Vehicle Bus Standard designed to facilitate communication between various modules within the vehicle. It enables interaction and coordination among microcontrollers and components, eliminating the need for a dedicated host computer. OBD scanners retrieve CAN data and convert it into a format that is easily understood through presentation and application layers. Look-up tables are used to decipher the received data. OBD functions as the higher layer, handling presentation and application aspects, while the CAN Bus serves as the communication layer, dealing with data transmission and physical layer issues [24].  
A wide range of OBD readers can be found in the market, spanning from as low as EUR 10 to several thousand euros in price. The most affordable devices typically utilize the ELM 327 chip [26] or its clones and offer limited functionality, providing only basic diagnostic capabilities. These support only SAE J1850 PWM (41.6 kbit/s), SAE J1850 VPW (10.4 kbit/s), ISO 9141-2 (5 baud init, 10.4 kbit/s), ISO 14230-4 KWP (5 baud init, 10.4 kbit/s), ISO 14230-4 KWP (fast init, 10.4 kbit/s), ISO 15765-4 CAN (11 bit ID, 500 kbit/s), ISO 15765-4 CAN (29 bit ID, 500 kbit/s), ISO 15765-4 CAN (11 bit ID, 250 kbit/s), ISO 15765-4 CAN (29 bit ID, 250 kbit/s), SAE J1939 (250 kbit/s), and SAE J1939 (500 kbit/s) and that makes these unsuitable for heavy duty vehicles. One of the advantages is that there are many mobile/PC apps supporting these low end OBD readers.  
Advanced, high-end OBD devices such as [27; 28; 29], catering to professionals, are available at a considerable cost, often ranging in the several thousands of euros. These devices are designed to support a wide range of OBD II protocols, ensuring compatibility with most vehicles. Additionally, they often offer proprietary OBD services specifically tailored for advanced diagnostics in repair shops. Alongside the hardware, these devices typically include the necessary software products required for comprehensive vehicle analysis and troubleshooting.  
In addition to the low-end and high-end options, there are also mid-range OBD readers available on the market. These devices offer additional functionalities and incorporate sophisticated IoT capabilities. For instance, products such as [30] provide real-time fleet monitoring capabilities, enabling users to track and manage a fleet of vehicles effectively. This trend highlights the direction in which OBD technology is evolving, moving towards connected OBD solutions that leverage connectivity and advanced features for enhanced vehicle monitoring and management [31].