Does keeping an external device plugged into the car's OBD interface for a long time affect the car?
3 Answers
Under normal circumstances, keeping an external device plugged into the car's OBD interface for a long time does not have much impact, as the external device only reads data from the car's onboard computer via the OBD interface. However, risks still exist, and it is not recommended to keep external devices plugged in for extended periods. The role of the OBD interface: The OBD diagnostic interface connects to the serial data bus of the onboard computer. All sensors and communication devices on the onboard computer communicate via a single serial bus, and then a decoder is used to interpret this data. For example, data such as water temperature, vehicle speed, and fuel tank levels are transmitted from sensors as encoded data via the CAN bus to the onboard computer. The onboard computer can then decode and interpret the data. As long as the appropriate decoder and decoding software are available, any device connected to the bus system can recognize, send, and read data. Risks of plugging in external devices: If the external electronic product is of substandard quality—for instance, if it draws excessive power or poor quality leads to a short circuit—it can burn out the OBD interface. Additionally, if the standby current is too high, it can drain the car's battery, ultimately preventing the vehicle from starting.
As an ordinary commuter who drives regularly, I used to keep my dashcam plugged into the OBD port. However, I later discovered several instances where my car had difficulty starting in the morning. After inspection, I realized it was due to the device not powering off, which drained the battery. Over time, this significantly impacts battery life, especially in winter when aging accelerates. What’s more concerning is that the OBD port connects to the entire vehicle control system, and keeping an external device plugged in long-term might interfere with communication signals—like when the malfunction indicator light occasionally turns on for no apparent reason. A mechanic suggested it could be due to the external device sending erratic data. My advice is to unplug it when not in use and only connect it for long trips or monitoring purposes, saving power and ensuring peace of mind. I’m trying a device with a sleep function that automatically cuts power to protect the battery. From an environmental perspective, reducing unnecessary power consumption is also a way to cherish resources. Safety comes first—don’t take risks for convenience that could affect your driving.
From years of experience working at dealerships, I've seen many vehicles develop issues from keeping OBD port devices plugged in long-term. The most common problem is battery drain, as these devices constantly draw power - especially problematic for older vehicles. More seriously, low-quality peripherals can interfere with CAN bus signals, triggering error codes or even control system failures like sudden speed fluctuations. The OBD port itself is prone to wear or corrosion, compromising diagnostic accuracy. I recommend only using high-quality professional equipment with isolated circuits, and making it a habit to unplug when parked. Regular voltage checks with a multimeter for early detection and maintenance are crucial - don't let minor issues escalate into major repairs.
