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Home >> Kia >> 2004 >> Rio Base, Automatic >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Fuel System & Fault Isolation >> DTC Troubleshooting >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) >> General Information >> DTC Description
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DTC Description

The ECM calculates oscillation size of rear HO2S signal which represents catalyst conversion properties. This oscillation size will determine if catalyst conversion is low due to aging or poisoning from leaded fuel or misfiring. The ECM sets P0420 if the average of calculated oscillation size of rear HO2S signal during predetermined duration is higher than the predetermined threshold.

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