Had the fault cleared on Tuesday. The fault was P4020 Catalyst System Efficiency Below Threshold (Bank 1). Just after start up today the CEL light came back again. The tuner adjusted the parameter and its been good until today.
Does anyone know what cell the catalytic converter is in the PHAT DP?
Rung Subaru today and they quoted me 410 for a new O2 sensor which is bloody steep!! Car is getting serviced tomorrow and going to run a diagnostic on it and drive the car and log some data to see what the sensor is doing. If all is good need to go back to the tuner in the afternoon to see what they can adjust but to me sounds like its kicking up the fault due to the higher flowing cat.
Maybe a new sensor is what it needs but trying to avoid that as its so expensive for troubleshooting purposes.