Xx 9xx notates input/output signals and controlsĭigits four and five show the specific failure code. Xx 1xx/xx 2xx show air and fuel measurements
Third digit shows us what system the trouble code references: Second digit shows whether the code is manufacturer unique or not: These codes, can either be generic or unique to the vehicle manufacturer.įirst unit identifies the type of error code: These codes are used to describe where an issue is occurring on the vehicle and are defined by SAE (you can find the whole spec here for a cost).
Learning how to work with those protocols also means that you can determine what that Malfunction Indicator Light (MIL) (aka the Check Engine Light) on your dash is referring to when it tells you there's an engine problem. Saving the planet is great (shout out to you citizen scientists!), but what this also means is we can access other features of the car and collect information from and on those parts. In other words, OBD is the language of the Engine Control Unit (ECU), and it was designed to help fight emissions and engine failures. OBD systems are designed to monitor the performance of some of an engine's major components including those responsible for controlling emissions. On-Board Diagnostics, or "OBD," is a computer-based system built into all 1996 and later light-duty vehicles and trucks, as required by the Clean Air Act Amendments of 1990. So what exactly is the OBD specification, and why do we care? According to the Environmental Protection Agency's website: The information provided is only intended for reading from the OBD-II spec. Warning! Modifying your OBD-II system to a non-certified state is considered a Federal Offense.