GF49.10-P-3033BK Monitoring Catalytic Converter Efficiency, Function

GF49.10-P-3033BK Monitoring Catalytic Converter Efficiency, Function







Each firewall catalytic converter is evaluated via its oxygen storage capability. A property of catalytic converters is that they are able to store oxygen. The oxygen stored during the lean phase is then reduced totally or partially during the rich phases. Aging reduces the ability of catalytic converters to store oxygen. It also reduces the ability to convert HCs.

By law, HC emissions must not go above certain limits. The task of the catalytic converter monitoring is to evaluate aging through the ability to store oxygen and therefore to convert hydrocarbons.

On catalytic converters at operating temperature and with enabled lambda control the O2 sensor signals downstream of catalytic converter are compared with the O2 sensor signals upstream of catalytic converter. The amplitude of the O2 sensor voltage downstream of catalytic converter must the smaller than the amplitude of the O2 sensor voltage upstream of catalytic converter (Note: if no monolith were installed in the catalytic converter for example, the O2 sensor signals upstream or downstream of catalytic converter would be identical).

Several measurements must be performed in the specified engine speed and load range. The results are compared with a performance map from the ME control unit and detected faults placed in the fault memory.

If a fault is detected, the engine diagnosis indicator lamp or the "CHECK ENGINE" indicator lamp (USA) is lit on the instrument cluster. The stored faults can be read out and erased with the STAR DIAGNOSIS.