04 WRX oxygen sensor problem

[gwpowell]

Hi, to anyone who may be able to help..

The o2 sensor on the front cat blew off while running the car, it seemed to build up pressure and "pop" it was hanging down with the hole to the cat open.

I have not had any problems with the sensor before, but I cant seem to fit it back. There is no thread on the sensor, it just sits loosley on top where it should be and there does not appear to be any clean breaks to any of the surrounding area.

I think the sensor is fine but does anyone know how to secure it back in place or why it happened in the first place.

Thanks.

[cheezycow]

Do you have an aftermarket uppipe?

[mycologist]

That is really unique. It blew out with the bung it is supposed to screw into. The thing on the threads of the sensor is part of the pipe - it was supposed to be welded on there.

If it is stock, maybe your cat got plugged and built up a ton of pressure.