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Home >> Chevrolet >> 2003 >> Tracker 2D Utility, 4WD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 2.0L >> Diagnostic Tests >> DTC P0420: Catalyst System Low Efficiency >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Check any for any heated oxygen sensor DTCs and diagnose those DTCs first. Are the DTCs P0131, P0132, P0133, P0134, P0135, P0136, or P0141 set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Install scan tool. Start engine. Run the engine until the normal operating temperature is reached. Verify that the engine is operating in Closed Loop. Run the engine 2500-3000 RPM for 3 minutes. Monitor the HO2S 1 and the HO2S 2 signals on the scan tool. Is the HO2S 2 signal as active as the HO2S 1 signal? If yes, go to step  5. If no, go to next step.
  4. Perform scan tool Clear DTC Information function. Operate vehicle within the Freeze Frame conditions or until P0420 diagnostic test has run. Did DTC P0420 set? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  5. Visually and physically inspect the TWC for any dents, severe discoloration caused by excessive temperatures, holes, or internal rattle caused by a damaged catalyst. Verify that TWC converter is a high quality part that meets the OEM specifications. Did you find a problem? If yes, go to step  8. If no, go to next step.
  6. Visually and physically inspect the exhaust system for any leaks, damage, loose or missing hardware. Repair as necessary. Was a repair necessary? If yes, go to step  9. If no, go to next step.
  7. Visually and physically inspect the HO2S 2 for pigtail and wiring harness making contact with exhaust pipe, a loose HO2S 2, or any road damage. Repair as necessary. Was a repair necessary? If yes, go to step  9. If no, go to next step.
    8. NOTE: Locate and repair cause of TWC failure before installing replacement TWC.
  8. Replace TWC. After repairs, go to step  10.
  9. Start engine. Warm engine to normal operating temperature. Ensure engine is operating in closed-loop. Operate engine at 2500-3000 RPM for 3 minutes. Using scan tool, monitor HO2S 1 and 2 signal voltage. Is HO2S 2 signal as active as HO2S 1 signal? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  10. Turn ignition off. Remove DOME fuse for 30 seconds (located in passenger compartment fuse block). Reinstall fuse. Reset radio clock time. Start engine and operate vehicle within the conditions for running the DTC or until DTC P0420 diagnostic test has run. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  11. Using scan tool, observe stored information and Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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