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Home >> Toyota >> 2003 >> MR2 C65M >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self Diagnostics >> Diagnostic Tests >> DTC P0420: Catalyst System Efficiency Below Threshold >> Possible Causes
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Possible Causes

DTC is set when both oxygen sensors have same amplitude after vehicle is driven for 5 minutes at 20-50 MPH. Possible causes are: