The 12mmx1.25 sensors are OEM. I replaced them myself, ordering them from based on recommendations from this site and shopping the various vendors selling them. I ordered for a '97 Defender and the ones I received fit properly in the old y-pipe. The motor is the original (GEMS). The truck had issues before I took it to the shop and when I brought it home from the shop, but the shop did not change the y-pipe or o2 sensors.
Originally Posted by NSGINC
Gems sensors are larger than cux. Are your 02 sensor connectors colored with orange and gray? You may have multiple problems due to your land rover being in shops that know nothing about them. You may have to work through the faults they installed before your vehicle is running correctly.