System Diagnosis: Notes

The self-diagnostic capabilities of this system, if properly used, can simplify testing. The Single-Board Engine Controller (SBEC) monitors several different engine control system circuits.

If a problem is sensed with a monitored circuit, a fault code is stored in the SBEC, the CHECK ENGINE light illuminates, and SBEC enters limp-in mode. In limp-in mode, SBEC compensates for component failure by substituting information from other sources. This allows vehicle operation until repairs can be made.

Once fault codes are known, refer to FAULT CODES  table in this article to determine the questionable circuit. Test circuits and repair or replace components as required. If problem is repaired or ceases to exist, the SBEC cancels that fault code after approximately 50 ignition on-off cycles. To clear fault codes, see CLEARING FAULT CODES  in this article.

A fault code does not condemn a specific component. Component is not necessarily the reason for failure. Fault codes pinpoint probable malfunctioning circuits.