All the code tells you is that the engine computer perceives an issue with the sensor's performance. Codes merely give you an idea of where to begin your diagnostic process.įor example, if you get a code for an oxygen sensor, that doesn't necessarily mean the sensor is faulty.
For example, SAE defines code P0740 as "Torque Converter Clutch Circuit Malfunction", whereas Chrysler refers to the code as "Torque Converter Out of Range".īecause the vehicle manufacturer's definition of a code may differ from that of SAE, it's a good idea to consult a repair manual or repair database for the code definition for your application.Īlso, remember that DTCs do not tell you exactly what's wrong with a vehicle. Sometimes the engine size and other factors also make a difference.Īnother thing to keep in mind is that automakers will often have a slightly different definition for an OBD2 code than the meaning supplied by SAE. Exactly which codes are supported will depend on the year, make, and model of the vehicle.
It’s important to point out that an individual vehicle will only support a portion of the available generic OBD2 codes. Other Noteworthy Information Regarding OBD2 codes.Today, OBD2 codes cover not only emissions-related powertrain and network systems, but also the chassis and body electronics. What's more, the diagnostic port for the tool to plug into was also standardized across all makes and models. OBD2 also ushered in a list of standardized DTCs that can be read with a generic scan tool or code reader. OBD2 builds on OBD1 by monitoring system functionality and being far more comprehensive overall. The second phase of OBD technology, OBD2, was introduced in 1996 and is still in use today. If a problem were detected, the engine computer would turn on the check engine light and store a diagnostic trouble code (DTC) in its memory. The agency's goal was for automotive computer management systems to continuously monitor engine-related components that could affect vehicle emissions.ĬARB required that all OBD1 systems monitor emissions-related electrical components for circuit problems. In 1988, the California Air Resource Board (CARB) began requiring all new vehicles sold in its state to be fitted with the first stage of OBD technology, referred to as OBD1. The technology eventually grew into what is now referred to as OBD2. The technology uses sensors and an on-board engine management computer to minimize vehicle emissions and improve driveability. Most automakers began fitting their cars with computer-controlled engine management systems in the 1980s.