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Home >> Chevrolet >> 2001 >> Cavalier LS, 2.2 4 >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (Engine Controls Self-Diagnostics - 2.4L) >> Diagnostic Tests >> DTC P0420: TWC System Low Efficiency (Bank 1) >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  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. Are there any other DTCs set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, go to next step.
  3. Use a scan tool to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC  . Does the DTC reset? go to next step. go to DIAGNOSTIC AIDS  .
  4. Turn ignition off. Visually and physically inspect exhaust system and rear HO2S for leaks. If a problem is found, repair as necessary. Did you find and correct the condition? If yes, go to step  6 . If no, go to next step.
  5. Replace the 3-way catalytic converter. After repairs, go to next step.
  6. Use a scan tool to clear the DTCs. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running this DTC. See CONDITIONS FOR RUNNING DTC  . Does the DTC run and pass? If yes, go to next step. If no, go to step  3 .
  7. 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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