Diagnostic Procedure

Diagnosis of the computerized engine control system should be performed in the following order:

1. Ensure all engine systems not related to the computer are operating properly. DO NOT proceed with testing unless all other problems have been repaired. Perform on-board diagnostic system check chart before using DTC charts.
2. If DTCs were displayed (other than DTC 12), determine whether DTCs are hard or intermittent. Hard DTCs cause Malfunction Indicator Light (MIL) to illuminate continuously with engine running. For diagnosing hard DTCs, proceed to appropriate diagnostic DTC chart. For diagnosing intermittent DTCs, proceed to INTERMITTENTS in TESTS W/O CODES - 1.6L article.
3. If DTCs were not displayed and a driveability problem exists, refer to SYMPTOMS in TESTS W/O CODES - 1.6L article. From there you will be sent to the appropriate area in the SYSTEM/COMPONENT TESTS - 1.6L article.
4. After repairs are made, clear DTCs, confirm closed loop operation and ensure MIL is not illuminated.