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Home >> Acura >> 2000 >> Integra GS-R, 2D Coupe >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold
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DTC P0420: Catalyst System Efficiency Below Threshold

NOTE: If DTC P0136, P0139 and/or P0141 is set, trouble shoot those DTCs before proceeding.
  1. Perform PCM reset procedure. SeePCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine and run at 3000 RPM, with transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Connect SCS service connector. See Figure. Test drive vehicle at 40-55 MPH for about 2 minutes. Decelerate for at least 3 seconds with throttle fully closed. Reduce vehicle speed and hold at 35 MPH until readiness code comes on. If DTC P0420 resets, go to next step. If DTC P0420 does not reset, problem is intermittent. System is functioning properly at this time.
  2. Inspect Three-Way Catalytic Converter (TWC) for plugging, melting, cracking, exhaust system leaks or TWC deterioration. Repair or replace as necessary.
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