The old favorite p0420!
This vehicle runs perfect, emissions data
co 0 %
HC o ppm
co2 15%
o2 0%
Leak tested ok, scoped both o2 sensors, front sensor activity normall to .8v, rear sensor activity normal flat line under most conditions,the ecm lamp came on again 3 weeks after erasing, I have read about super market fuel causing issues could this realy be a fix?, I have also read about a "re-flash" on the working tolerances of cat performance? your thoughts would be helpfull.