My old 93 ford aerostar panel van

In the past couple of years, I have replaced the oxygen sensor about 2mth after the the guarantee is over. I have bought these sensors from places like N A P A and they are original replacement. I don’t understand why they keep going bad, other than just getting bad ones. Is there any other reason anyone knows why they keep going bad, or anything else I should change? Let me know Thanks Phil. P S maby I should get the next ones from autozone.

When you remove the sensor is the cone burned away? Or possibly coked up? Or is a wire burned or chafed? There are several ways to fail.

Rather than stepping down in quality to AZ, step up to OEM maybe. I think for that vintage though its kind of a maintenance item with replacement at 30-50K intervals.