What can be connected to OBD?
3 Answers
OBD interface itself is not designed for external connections. External devices may affect the vehicle itself through the OBD interface due to their own malfunctions or issues. OBD is a diagnostic system extended for vehicle fault detection, primarily to monitor the engine status and exhaust conditions. In its early stages, OBD could only report faults via indicator lights. Later, OBD became capable of reporting various real-time data and standardized fault codes, revolutionizing automotive fault diagnosis and repair methods. OBD devices monitor multiple systems and components, including the engine, catalytic converter, particulate filter, oxygen sensors, emission control systems, fuel system, EGR, etc.
I've always been curious about the various ports in cars, especially the one called OBD interface. I've tried plugging in several devices myself, the most common being the fault code scanner—last time the dashboard warning light came on, I used it to identify an oxygen sensor issue. You can also connect those little Bluetooth adapters, then use a phone app to monitor real-time fuel consumption and coolant temperature, which is super useful on long trips. Some tuning shops even use it to activate hidden features like automatic window closing when locking the car. But be careful—randomly connecting devices might affect the car's computer; my neighbor once drained his battery by using a cheap GPS tracker. Oh, and nowadays those driving behavior monitors that insurance companies give out also rely on this port for data.
Having repaired cars for over a decade, the OBD port is practically a master key in our line of work. At the most basic level, it's used to connect diagnostic computers for reading and clearing trouble codes—no problem at all. More advanced uses include flashing ECU programs to help car enthusiasts boost horsepower. During routine maintenance, we often connect data loggers to monitor engine conditions, which is far more accurate than judging by sound alone. Once, we encountered a flood-damaged car and relied on the OBD port to connect an emissions analyzer, which revealed the catalytic converter was beyond repair. Recently, telematics devices that plug into this port have become popular, but I'd advise against buying cheap, no-name brands—last year alone, I fixed three cars whose fuses blew due to short circuits from aftermarket devices.
