On-Board Diagnostics

Engine Control Module (ECM) monitors engine operation and contains a self-diagnostic system which stores Diagnostic Trouble Codes (DTCs) and complies with On-Board Diagnostics Generation II (OBD-II) standards.

Federal Test Procedure (FTP) sets maximum allowable emission standards. Malfunction Indicator Light (MIL), labeled CHECK ENGINE light on instrument cluster, must illuminate if a system or component either fails or deteriorates to a point where the vehicle emissions could increase to more than 1 1/2 times FTP standards.

If malfunction does not recur in 3 ignition cycles, MIL goes off, but DTCs remain recorded in ECM memory. DTCs may only be retrieved using an On-Board Diagnostic-II (OBD-II) scan tool that complies with SAE standard J-1978 or Subaru Select Monitor connected to Data Link Connector (DLC). Scan tool also provides freeze-frame data and can be used to clear codes.