Review on Dorman 904 549 Nitrogen Sensor Repair by Gregory Shin

Bought for Mercedes ML320. This is a piece of metal that is difficult for them to spoil. However, I had to thread an M20x1.5 tap through to expose the threads a bit before the NOx sensor fitted properly. Luckily I was at my friend's mechanics store and he had a faucet handy. Mind you, that was before I welded it in place so it wouldn't warp from the heat. Maybe the one I got was the last one made with a worn cutting tool or tap? I am not sure. The thread was M20x1.5, slightly out of tolerance. If you work on diesel engines regularly, it's worth buying a faucet to clean the threads in your existing plugs, as well as a threaded head to clean the NOx sensor threads.