What is the exact free-air calibration procedure for Innovate wideband controllers?

Follow the timing exactly: (1) power on without the sensor connected for about one minute; (2) power off; (3) connect the sensor, out of the exhaust in free air, and power on for about one minute until calibration completes; (4) power off; (5) install the sensor in the exhaust and power on. Skipping the waiting times is a common reason for calibration failures.