DTC P0420: Catalyst System Low Efficiency: Condition
WARNING: This page is about a different car, the 2002 Suzuki Vitara. However, it is still accessible from the selected car via links, so may be relevant.
DTC is set when value from HO2S No. 2 becomes closer to value from HO2S No. 1. MIL is illuminated when Power Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:
- Exhaust system malfunction.
- Catalytic converter malfunction.
- HO2S No. 2 malfunction.
- Fuel system malfunction.