more than likely you could repair the harness. did the cat tech confirm that it is the correct ECM year to match the pressure sensor on the throttle body?
The most likely spots for it to be the harness is right close or in the plug itself to the pressure sensor on the throttle body, or where that.
it is worth noting that, unless MCFA changed it, this harness (and all the related to the emissions control components even the spark plugs) have a much longer warranty period than the standard truck. some as long as 3500 hours. it might be worth checking if the truck is less than 3 years old.
While MCFA may not yet produce a listing that provides part number for the many different plugs used in the wire harness, there is plug kit for the sensor, but it was not listed in the parts manuals, it was provided in a tech support bulletin from about 2005 for changing the throttle body to update the throttle body to match newer ECMs that use the different sensor