My friends is300 just recently had an electric exhaust cutout installed right before the muffler. Not long after the installation, the code p0156 showed up. looking at the sensor on the obd2 app, it shows that it has zero voltage. Its not reading anything??? Could it be that the sensor just coincidentally broke at the same time of installing the cutout? or could the cutout be causing an issue. If so, how could it cause a problem when the muffler and 02 sensor are very far apart. He now needs to pass CA smog inspection so he decided to remove the cutout and weld back on the stock exhaust piping.