Replaced 3 O2 sensors so far after using a diagnostic scan tool. Things looked good for about an hour now almost every sensor I replaced has gone bad. They are Bosh sensors. Could it be cheep sensors or somthing else that has gone bad? This is a Dodge Intrepit with a 2.7 eninge. 2 of the three sensors are front bank sensors and the third is a rear sensor that I didn't yet replace that is showing bad.