So...I'm one of those afflicted with a cat conv that broke inside and slid forward and chopped the nose off the O2 sensor.

I've got to get a new O2 sensor and either a used OEM cat or I'm thinking of the Berk HFC. But in the mean time I've got a track day possibly scheduled for this weekend and I'm wondering if a nonfunctioning rear O2 sensor affects engine performance much.

On my Android phone I've got the app Torque, and I have the bluetooth dongle to attach to the OBD port. This allows me to look at fuel trim measurements, but I've got no idea what they should be in the first place.

Main question is: would the broken O2 sensor affect my horsepower?

 

I would Fix it before the track day. You will have a CEL until you fix it. On the track if you don't you will not know if you are having other issues. So rule of thumb only track a car that is 100% good working order.

 

so it's rear sensor?
check wether it cuase the engine run at OPEN loop or it's still Close.

 

David, if its the secondary, it won't affect you at all. It's there only to make sure your cat is working properly.

06+ cars can completely disable it via Flashpro.

 

The upper o2 sensor before the cat is the sensor that measures the cars air fuel mixtures, the one down stream of the cat simply monitors the catalatic converters efficency. I would still replace it though no body wants a check engine light !

 

if you need to fix it anyway, why bother to wait?

esp when you can have multiple CEL on the track and there's no way to tell on the fly.

 

No time to fix...need a used cat and then the time to put it on....but it'll be done next week.