I had been having a problem with the NGK/NTK O2 sensors on my car. Finally decided to go with Bosch this time. So far I've had no issues. All my other NGK/NTK parts never have issues, but the O2 sensors seem to be a part they don't put their quality into. Bosch is quite a bit more expensive, but enough searching and I found it for a relatively cheap price from this ebay vendor.