DTC P0420: Catalyst System - Low Efficiency: Condition
DTC is set when Engine Control Module (ECM) detects that value from HO2S-2 becomes closer to value from HO2S-1. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible causes are:
- Catalytic converter malfunction.
- Exhaust system malfunction.
- Fuel system malfunction.
- HO2S-2 malfunction.