I'd just get the good sensors from Oxygensensors.com or AB. In the last 6 months I've gone through 4 Bosch pre-cat sensors. First two lasted only about 5 months....second two checked bad in about 20 minutes or use. Got some from AB and 6K later still good. I did get the bosch sensors from autozone and then advance auto, maybe there was a bad batch in this part of the country. Doesn't matter though I'm done with Bosch sensors.