My 2009 Camry check engine light is on. Dealer said the two O2 sensor both are dead and need to replace. After dealer reset the check engine light I have driven two days for 50 miles and the check engine light doesn't come back. If the O2 sensor is bad how long does it take for check engine light on again? Is it possible the check engine report on by mistake since two O2 sensors got bad at the exact same time is really rare. Thanks for help!