Circuit Description
Three-Way Catalytic (TWC) converter controls emissions of hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NOx). Catalyst within converter promotes a chemical reaction which oxidizes HC and CO present in exhaust gas, converting them into water vapor and carbon dioxide. Catalyst reduces NOx, converting it to nitrogen. VCM monitors this process using HO2S located in exhaust stream after catalyst.
HO2S produces a signal indicating oxygen storage capacity of catalyst and indicates catalyst's ability to convert exhaust emissions effectively. If catalyst is properly functioning, HO2S signal will be less active than other HO2S located further upstream from catalyst. DTC P0430 will set is HO2S signal is outside of acceptable range for an extended period of time, indicating 3-way catalytic converter oxygen storage capacity is below acceptable threshold.
DTC will set when the following conditions are present:
- No VSS DTCs are set.
- No TP sensor DTCs are set.
- No HO2S DTCs are set.
- No misfire DTCs are set.
- No MAP sensor DTCs are set.
- No fuel trim DTCs are set.
- No ECT sensor DTCs are set.
- Engine coolant temperature is greater than 185°F (85°C).
- Vehicle is in "closed loop" fuel control.
- Listed conditions are met for a period of time to ensure a warm catalyst (at least 2 consecutive minutes).
- Calculated engine load is steady.
- Vehicle speed is steady between 20-70 MPH.
- Catalyst monitored HO2S signal activity has been determined to be excessive by VCM.
- Listed conditions are met for up to 2 additional minutes after catalyst warm-up criteria has been met.