It's most likely that those two codes are really caused by a vacuum hose leak, not O2 sensors. Carefully inspect the vacuum hoses by the intake manifold behind the PS pump (if turbo) and at its other end where it's routed to the air intake hose opposite a sensor, lower area where the intake hose attaches to the turbo. If not turbo, remove the plastic throttle body cover and check at the vacuum T and check the flame trap hoses.