M103: Oxygen sensor keeps being destroyed
 

Hi everybody
On my 300TE from 1992, 181 kmilee, the oxygen sensor keeps getting destroyed after about three days. Everything works fine when I put in the new one: It passes emission test, I can adjust duty cycles etc.
After about three days, the "check engine" light is on, and there is voltage output from the sensor. The engine is in good shape (recent headjob, starts very well, revs fine etc).
So what could destrouy the oxygen sensor? Heat? Some chemical in the exhaust?
Thanks for any insights.
Bruno

I would think that fuel "quality" or some additive was causing that problem.

I would drain all of the fuel & start with a new tank, Sometimes the heater control won't completely power-up the heater circuir in the sensor.

Have you made sure that the heater circuit for the O2 sensor is working.

Have you done any repairs using Silicon gasket maker ?????????

thanks for the tips
 

No, I have not used any silicone-containing sealant.
I'll check the heating and drain the fuel.

Found the reason
 

Just wanted to report back as I have identified the problem.
It seems like excessive heat destroyed the oxygen sensor.
Actually, I used some heat-shielding tape to wrap the exhaust including the catalytic converter. While I removed some of that tape on the pipes before the oxygen sensor, it was the heat coming from the catalytic converter that killed the oxygen sensor. After I removed the tape around the converter, the sensor (the fourth one...) does not get destroyed anymore.
Thanks for your suggestions, Bruno

Before I read your very last post, I was gonna theorize that your catalytic converter may be clogged causing heat to build up in the area..... I think this might be very likely now

Heat shielding may be masking the actual problem of your converter getting way too hot.

You should check that out because a clogged cat converter can, in extreme cases, catch the car on fire.


J.