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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 274 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold >> Conditions For Running DTC

Conditions For Running DTC

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

This DTC is sampled once at an idle when the above conditions are met. If the first test fails, the ECM will take more samples during the current ignition cycle or may take samples for up to 6 ignition cycles. The extra sampling is to ensure that a converter has failed, not just temporarily poisoned.