As the efficiency of the catalytic converter drops through deterioration, the switching rate of the rear O2 sensor signal will start to look like the front O2 sensor signal. When the rear O2 sensor signal reaches approximately 75 percent of the front O2 sensor, which of the following is the result? A. The diagnostic trouble code is stored with the MIL on.
B. A one-trip flag is set with a code stored, but the MIL isn't activated.
C. The catalytic converter should be replaced.
D. The catalyst beads in the converter should be changed. ​