40 TWC Conversion, Bank 1 - Above Limit

P0420

40 TWC Conversion, Bank 1 - Above Limit

Function
In order to assess TWC (three-way catalytic converter) conversion, the oxygen storage capacity of the TWC is determined by comparing the oxygen sensor amplitudes after the TWC. If oxygen storage capacity is reduced due to ageing of the TWC, then the conversion of the TWC is also diminished, and the amplitudes of the oxygen sensors after the TWC are increased.

Diagnosis conditions







NOTE: If an ageing oxygen sensor is recorded in conjunction with a fault in the TWC, a check must be performed with a new oxygen sensor to see whether a TWC fault is still indicated.

P0420 - P0430:

NOTE: In the case of a catalytic converter fault in the Boxster (2.7l and 3.2l), only the pre-catalytic converter is to be replaced.

Diagnosis Procedure