I purchased my '95 530i 3 years ago and have had to replace both oxygen sensores twice already. Before the second replacement the head gasket was replaced and I thought the problem was finally fixed. Now "check engine" light is on again (less than a year later)! I'm almost certain it's the oxygen sensors again. The car has 96K. Why are my oxygen sensors getting burned out every year!?! Please help. Thanks.

Glinthi