Using an OBD-2 reader to diagnose and troubleshoot car issues is a great way to save time and money. But before you start using one, it’s important to know if there are any legal limitations. Understanding the laws of your state or country can help you avoid potential fines or penalties. To begin with, some areas may require that only certified professionals use OBD-2 readers on vehicles. For example, in the US, emissions testing centers may only be able to perform tests if they have a certified technician available. This means that do-it-yourselfers will need to find another way to diagnose their vehicles' issues. Some states also limit the amount of information that can be gotten from an OBD-2 reader. This is usually done to keep users from seeing information about how drivers act, like when they drive too fast or speed up quickly. In these cases, it’s important for users to check their local laws before attempting any diagnostics with their OBD-2 reader. Also, it's important to know that many car makers offer their own diagnostic software that can be used with an OBD-2 reader. While this type of software normally provides more detailed information about a vehicle’s systems than the generic OBD-2 reader alone, it may not be compatible with all makes and models of vehicles. So it’s always best to check compatibility before buying this type of software or hardware device. In short, using an OBD-2 reader can give you a lot of useful information about your car, but you should check the laws in your area before doing so. Knowing what types of data are restricted and which diagnostic software is compatible with your vehicle can help you get the most out of your investment while avoiding any potential penalties or fines down the line.