Diesel Oxidation Catalyst

The oxidation catalytic converter is monitored with regard to its conversion ability which diminishes with aging. The conversion of hydrocarbons (HC) during cold start is used as the indicator as heat is produced as part of the chemical reaction and it follows a defined temperature progression after the oxidation catalytic converter.

The exhaust gas temperature sensor after the oxidation catalytic converter measures the temperature. The DDE maps the temperature progression during cold start and compares it to calculated models. The result determines how effective the oxidation catalytic converter is operating.

A reversible fault is stored if the temperature progression drops below a predetermined value. If this fault is still determined after two successive diesel particulate filter regeneration cycles, an irreversible fault is stored and the MIL is activated.