It could be the metal tube, which is what is left of the sensor, is expanding as the extractor is tightened in and jamming it even more.
If you can feel the extractor springing slightly as you attempt to turn it, then it is close to the limit and about to snap. If it has not moved by that point I would be inclined to give up trying with the extractor and try the alternative....
You need a drill sized or ground to match the smaller diameter of the thread. Drill through with that carefully, a little at a time, adding plenty of grease regularly to collect any swarf. Take it out often to wipe the grease, plus swarf off and regrease with fresh clean grease. Then just hope none of the swarf goes inside and your hole was centred on the remaining bits of sensor. Next you try to tease out the remnants of the sensor in the thread with a large sharp sewing needle, if there is any left, plus a pair of tweezers or long nose pliers.
If that doesn't work - all you can do is drill (using grease as above) it and tap it over size with an Helicoil kit, to suit your sensor.
What ever does work, if you have any doubts about any metal getting in, the engine will need flushing with the engine run briefly, to flush the debris out of the oil gallery before the new sensor is fitted - so the oil pressure force it out.
If you can feel the extractor springing slightly as you attempt to turn it, then it is close to the limit and about to snap. If it has not moved by that point I would be inclined to give up trying with the extractor and try the alternative....
You need a drill sized or ground to match the smaller diameter of the thread. Drill through with that carefully, a little at a time, adding plenty of grease regularly to collect any swarf. Take it out often to wipe the grease, plus swarf off and regrease with fresh clean grease. Then just hope none of the swarf goes inside and your hole was centred on the remaining bits of sensor. Next you try to tease out the remnants of the sensor in the thread with a large sharp sewing needle, if there is any left, plus a pair of tweezers or long nose pliers.
If that doesn't work - all you can do is drill (using grease as above) it and tap it over size with an Helicoil kit, to suit your sensor.
What ever does work, if you have any doubts about any metal getting in, the engine will need flushing with the engine run briefly, to flush the debris out of the oil gallery before the new sensor is fitted - so the oil pressure force it out.