How many OBD interfaces does a car have?
3 Answers
Currently, most cars use a single ECU for the engine, transmission, ABS, etc., meaning there is typically only one OBD diagnostic interface. Explanation of OBD: OBD is translated into Chinese as "On-Board Diagnostics." This system continuously monitors the engine's operating conditions and the working status of the exhaust after-treatment system. Notes on OBD: When a fault occurs in the system, the Malfunction Indicator Lamp (MIL) or Check Engine warning light will illuminate. Simultaneously, the OBD system stores the fault information in memory. Using standard diagnostic tools and interfaces, this information can be read in the form of fault codes. Based on these fault codes, technicians can quickly and accurately determine the nature and location of the issue.
As a mechanic who works with cars every day, I can tell you definitively that the vast majority of household vehicles have only one OBD port. This standard 16-pin interface is usually hidden near the knee position under the steering wheel, just like a universal data socket in every car. All the Japanese, German, and American cars I've repaired follow this design, mainly to allow diagnostic tools to uniformly read fault codes. However, be aware that some engineering vehicles or special-purpose vehicles may have additional ports, but ordinary car owners don't need to worry about this at all. Just remember that the trapezoidal socket under the steering wheel where you plug in the diagnostic tool is the OBD port.
A veteran driver with 20 years of car experience shares insights: Over 90% of passenger cars today feature a single OBD port design, just like my old Passat and my son's new Tesla. This standardized interface, which became widespread in 1996, is incredibly important. Last time my engine warning light came on, it was through this port that I diagnosed an oxygen sensor issue. The port isn't always located under the steering wheel—some French cars hide it behind the ashtray, while SUVs might place it on the side of the center console. Although some modified cars may have additional ports, factory vehicles never come with two standard OBD ports simultaneously.
