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Home >> Saturn >> 2002 >> SL2 Automatic, MP6 >> Repair and Diagnosis >> External Pages >> Different car >> Section 12 (Engine Controls Self-Diagnostics - 2.2L CNG) >> Inspection/Maintenance Procedures >> Inspection/Maintenance System Check >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Many DTC related repairs will instruct technician to clear DTC information. This procedure will reset ALL I/M System Status indicators to NO and require performing I/M Complete System Set Procedure.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. Repair any DTCs or driveability concerns that may prevent I/M System Status tests from completing. If DTCs or driveability concerns are found and repaired, go to step  3 . If no DTCs or driveability concerns are found and repaired, go to next step.
  2. Check Technical Service Bulletins (TSB) for software updates that may prevent I/M readiness. Perform any reprogramming or repairs indicated by service bulletins. When complete, go to next step.
  3. Using scan tool, observe the I/M System Status display for the PCM. Are any of the tests indicating NO? If yes, go to next step. If no, go to step  6 .
  4. Turn ignition off. Remove CNG fuse (20-amp) from underhood fuse block. Start engine and allow to idle. Using scan tool, verify engine is operating in gasoline mode. Perform necessary set procedures for I/M System Status indicators that were set to NO. When complete, go to next step.
  5. Turn ignition off. Reinstall CNG fuse. Start engine and allow it idle. Using scan tool, verify engine is operating in CNG mode. Perform necessary set procedures for I/M System Status indicators that were set to NO. After performing set procedures, system is okay.
  6. Start engine and allow to idle. Using scan tool, verify engine is operating in CNG mode. Perform necessary set procedures for I/M System Status indicators that were set to NO. After performing set procedures, system is okay.
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