DTC P0420: Catalyst System - Low Efficiency: Condition
WARNING: This page is about a different car, the 2003 Suzuki Vitara. However, it is still accessible from the selected car via links, so may be relevant.
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.