I have a 91 loyale that I use strictly for getting up the ski hill in the winter. The exhaust system has had the Catalytic converters removed and runs a straight pipe to the muffler as the system is replaced every other year due to rust. Now my check engine light has come on and the code says it is the O2 sensor. Do I even need this sensor without the Cat converter's? Performance did not change at all since the O2 sensor quit. We have no emissions testing here so that is not a issue.

Is there any reason to replace the sensor other than getting the light to reset?

Well, is it fuel injected? If so, it helps with the Air to Fuel ratio. It's a $20 part, no reason, other than money, not to change it.

 

As for the exhaust rustin out, ever thought of painting it with some cheap high temp paint? To see if that would slow down the oxidizing?

Yes it is fuel injected. I just wondered as it did not seem to affect my fuel mix on the way up the hill today, ie: no pinging, usual power, no smoking from too rich a mix. The sensor is $89.00 canadian up here which is affordable unless I am throwing it away for naught. I have not tried paint, just cheap muffler and pipe makes it 175.00 every other year.

I know this sounds stupid...but...spray WD-40 on the underside when you KNOW you're going to be done for the season and park the car on a tarp. When the next season comes around, clean it off with Brakleen or some other NON-FLAMMABLE solvent (thorough hosing would work too). Should last longer if water/air can't penetrate the oil coating.

 

(Obviously, do not drive it immediately after soaking the exhaust in oil. )

Been there done that. Helps a bit , very messy and smelly.