DTC P0420: Catalyst System Efficiency Below Threshold: Condition
WARNING: This page is about a different car, the 2003 Suzuki Aerio. However, it is still accessible from the selected car via links, so may be relevant.
DTC is set when 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-1 malfunction.
- HO2S-2 malfunction.