P0430
swap O2s and see if the code follows ("reset" the PCM after swapping)
if it follows... then it's a bad o2 sensor... if not it's a bad cat (likely bat cat)
now... if it's a bad cat... GM recently extended the warranty on cats due to problems... (EPA requires 8 year/80k mile... i think GM extended to 10k/100k mile) ... though don't know if it applies to 98s ... I know 00-02 were covered



