I have a p0420 p0430 randomly on this car no exhaust leaks i.e. manifold Has about 110k oe copper ngk plugs replaced every 30k synth oil 5,000 mile intervals with MOA additive.

Premium 91 octane used since new.

scope o2 sensors with a 4 channel lab scope wave form looks very good. I did recently with in last year add a k and n air filter to this other wise bone stock any ideas ? comments

John Godwin
Owner
John's Automotive Diagnostics
Golden, Colorado, USA