Here is some info for the code you have. (Exhaust Leak Is on the list.)
P0430-CATALYST EFFICIENCY (BANK 2)
Theory of Operation
The State of Change (SOC) catalyst monitor uses the signals from both the upstream and downstream O2 sensors to detect aging of the catalyst. Based on the fact that when a catalyst ages, it loses some of its Oxygen Storage Capacity (OSC). As a result, part of the untreated exhaust gases can breakthrough the catalyst and causes the downstream O2 sensor to deviate from its neutral (Stoichiometric) position. By observing the activities in the downstream O2 signal, the degradation level of catalyst can be detected. In general, the higher the downstream O2 sensor SOC value, the more exhaust gas breakthrough and the lower the OSC of the catalytic converter.
When Monitored:
ECT above 70° C (158° F), engine RPM between 1400 and 2300, vehicle speed between 64 and 96 kph (40 and 60 mph), and engine run time greater than 3 minutes.
Set Condition:
If the final State of Change index is within the calibrated fail threshold. Two trip fault. Three good trips to turn off the MIL.
Possible Causes
O2 RETURN UPSTREAM CIRCUIT SHORTED TO GROUND
O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO GROUND
O2 RETURN UPSTREAM CIRCUIT OPEN
O2 RETURN DOWNSTREAM CIRCUIT OPEN
EXHAUST LEAK
ENGINE MECHANICAL CONDITION
AGING O2 SENSOR
CATALYTIC CONVERTER
