"exhaust troubles"

[blackthunder]

i have recently fitted a exhaust system to my vz V6 thunder ute (pacemaker extractors, high flow cats and a lukey exhaust). a couple days after fitting it the "check powertrain" alert came up on my computer. i took it to holden and they said the high flow cats were bot burning enough emissions and they could not fix it. they also said it was not the oxygen sensors. an performance mechanic said he can override it with a performance tune for 900 bucks?? anyone have any information??

[Not_An_Abba_Fan]

If the car has 4 O2 sensors then this is a common problem. The back two sensors read how efficient the cats are by comparing the signal to the front two sensors, and because I would put money on the fact that the cats you have gotten are not EPA compliant, they are not working enough, so the PCM picks up the error.

[blackthunder]

can this mechanic just turn these sensors off without the tune and the 900 bucks?