I have 96 chev truck 305 CI with 228,000 miles on it. trouble code comes up
with catalyist efficiency below threshold bank 1. It has 4 02 sensors and 1
catalytic converter. I clear the codes and it runs fine for a couple of
days up to a couple of weeks. Cant figure out if 02 sensors or converter
is bad.

hosbadar wrote:
> I have 96 chev truck 305 CI with 228,000 miles on it. trouble code comes up
> with catalyist efficiency below threshold bank 1. It has 4 02 sensors and 1
> catalytic converter. I clear the codes and it runs fine for a couple of
> days up to a couple of weeks. Cant figure out if 02 sensors or converter
> is bad.

Neither can we, but if you take it to someone who has the good $7,000
OBD II gear, they can. Guessing only on what you posted, it seems more
likely the converter OR another operating, ignition or mixture issue
possibly causing the insufficient catalyzation symptom. This, too, is
where the higher-end gear is worthwhile.