H2o sensor

Hello, Most oxygen sensor failures result in the use of excessive amounts of fuel, as the engine's processor cannot determine the proper amount of oxygen in the exhaust stream, either before and/or after the catalytic converter. Your concern would be performance related, excessive fuel consumption, and a check engine light usually. To be clear, though, other things can also cause those symptoms and "lean" running codes, so you really need to have a proper diagnostic test performed before guessing at a sensor replacement.