2008 Mazda 3 O2 sensor replacement

[xxch4osxx]

I finally got around to replacing the original O2 sensor in the girlfriend's Mazda yesterday. This is the pre-cat sensor. The car has 273,000kms on it. After-cat sensor was replaced last fall. I was surprised how easy it was to get out. Not seized at all. One good reef on the ratchet and it came loose. NTK sensor went in to replace it.

 

[Number_35]

They put a dab of anti-seize compound on the threads at the factory. You probably found a small packet of same with the new sensor. I wish they applied it to more parts than that.

 

[xxch4osxx]

Originally Posted By: Number_35
They put a dab of anti-seize compound on the threads at the factory. You probably found a small packet of same with the new sensor. I wish they applied it to more parts than that.


Ya, there was a plastic piece that was threaded on and that kept the anti-seize in place on the NTK sensor. The after-cat sensor was a bear to get out. Ended up having to cut it off, drill it out and weld a new bung for the replacement sensor to thread into.