After 7 months the sensor has fully failed. Replaced both the sensor and pigtail - but oil is leaking through the sensor body pretty badly and it's giving bad readings. Unplugging the sensor (using default PCM values) and the truck runs a lot better - proving the sensor has failed. Going to look into ordering the CAT version of the sensor to replace this. $300 for 7 months of usage is a steep price to pay.