On-Board Diagnostics System: Function

The on-board diagnostics system detects and store in the form of a code a fault that has occurred in any of the following input and output signal systems.

Fig 1: On-Board Diagnostics System Monitored Input & Output Signals Chart

Courtesy of SUBARU OF AMERICA, INC.

If a fault has been detected, the system tells the fault by causing the AT OIL TEMP warning light to operate as follows:

• Repeated flashing at 4 Hz frequency ...Errors such as battery trouble
• Repeated flashing at 2 Hz frequency ...No faults in the system
• Flashing at different intervals and frequencies ...Diagnostic trouble codes of corresponding faults
• Continued illumination of light ...Fault in wiring