OBD System General Description

The OBD system consists of several diagnostic devices that monitor individual emission control system parameters and record detected faults in the onboard processor memory as individual diagnostic trouble codes (DTCs). The system also checks sensors and actuators, monitors vehicle operating cycles, and provides the ability to freeze data and clear memory.

All models described in this Manual are equipped with the second-generation On-Board Diagnostics system (OBD-II). The main element of the system is the onboard processor, most often called the Engine Control Module (ECM) or Powertrain Control Module (PCM). The PCM is the brain of the engine management system. Input data is received by the module from various information sensors and other electronic components (switches, relays, etc.). Based on analysis of data from the sensors and the base parameters stored in the processor memory, the PCM issues commands to activate various control relays and actuators, thereby adjusting engine operating parameters and ensuring maximum engine output efficiency with minimum fuel consumption. OBD-II processor memory data is read using a special scan tool connected to the 16-pin Data Link Connector (DLC) located under the instrument panel on the driver's side of the vehicle.

In principle, trouble codes stored in the self-diagnostic system memory can be read using a jumper wire installed between specific terminals of the 16-pin diagnostic connector.

Components of the engine control/emission control systems are covered by special extended warranty obligations. Do not attempt to perform PCM fault diagnosis or replace system components until these warranty obligations expire; contact authorized Honda dealer service centers.