Catalyst Test Fail Threshold

The display indicates seconds from -25.6 to +25.5. This display indicates the passing value for Oxygen Storage content of the exhaust catalyst. This value is used to pass or fail the idle catalyst test (P0420). This display will be fixed at a slightly positive value until DTC P0420 fails. Once failed this value is set to 0.0 seconds until the idle catalyst test (P0420) passes. Although comparing this display to the Catalyst Test Time Difference EWMA may aid in determining if a catalyst is failing always allow the idle catalyst test (DTC P0420) to pass or fail a catalytic converter.