Ford
Type:
    Powertrain - Auxiliary Emission Controls - ISO/SAE Controlled
Description:
    Catalyst System Efficiency Below Threshold Conditions
Cause:
    Engine running at steady state highway conditions for 5 minutes in closed loop, then the PCM detected that the rear HO2S switch rate was too high

Generic
Type:
    Powertrain - Auxiliary Emission Controls - ISO/SAE Controlled
Description:
    Warm Up Catalyst Efficiency Below Threshold