Are you sure you wired it EXACTLY according to the instructions? Grounds are critical on wideband so if they told you to ground something to the rearview mirror, you ground it to the rearview mirror.

The only reason I ask is you is said you installed a different one that did the same thing.

I have an Innovate LC1 and the common theme in the tech forum on questions about sketchy readings all revolved around grounds attached other than instructed.

Kevin