How long since a tune-up? 02 sensors are part of a tune-up. Check for applicable trouble codes. You should be able to check mil codes, yourself. You use a jumper wire at the A & B terminals at the datalink connector. Turn key just till the dash lites come on, no further. Then the mil on the dash starts flashing, you count the flashes to get the codes. Your looking for two digit codes. Let us know what you find.