Aftermaket exhaust, PO420 code?

[AlaxyGalaxy]

Could it be that I didn't tighten the spring bolts enough and that oxygen is seeping un at the downpipe gasket?

What about the anti seize compound fumes?

[Rigaud]

Originally Posted by AlaxyGalaxy

Could it be that I didn't tighten the spring bolts enough and that oxygen is seeping un at the downpipe gasket?

What about the anti seize compound fumes?

A leak can cause it but usually OB2 systems are too slow to detect that. Not like German VAG-COM that detects anything in a fraction of a second. Anti seize depending how much you put and how far in maybe but it would burn off quick. Temps are 500celcius plus. Maybe CT Scott will show up or someone else.

I replaced my exhaust system from header to tail pipe myself over 2 years ago, Magnaflow Cat and mid resonator freeflow. Welded my own bugs for 02 sensors no issues.