P0140 after spark plug non fouler install on system with cat

[tpeters]

I recently did the spark plug non-fouler trick to clear code p0142 on my 2004 mazda 3 to pass emissions next month. After about 20 miles, I got code P0140 "No o2 activity detected". This is not a catless system, does this trick not work on vehicles with the stock catalytic converter still installed? Has anyone else had this issue? what do I need to do to fix it?

 

[xxxmonoxidechil]

That code sounds like the sensor got unplugged.