Customer Ready to JUNK This Malibu? (Intermittent REDUCED POWER)

Customer had his 2011 Chevy Malibu towed to PHAD from 4 hours away because his Parts Cannon is OUT OF AMMO! This Chevy INTERMITTENTLY goes into REDUCED ENGINE POWER limp mode...but I CANNOT recreate the customer complaint...It runs great! The P0641 - 5V1 Reference Circuit DTC is a big clue... My gut tells me a harness is rubbed through, but locating the damaged harness is easier said than done! How do we attack this INTERMITTENT problem in the shop? THINKTOOL PROS: ****$170 OFF!!**** https://www.amazon.com/dp/B08XXWHQVJ?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B08XXWHQVJ&asc_item-id=amzn1.ideas.NHZL00NIDEPF&ref_=aip_sf_list_spv_ofs_mixed_d_asin REFRIGERANT L:EAK DETECTOR: https://www.amazon.com/dp/B095S6S6GY?linkCode=ssc&tag=onamzpineholl-20&creativeASIN=B095S6S6GY&asc_item-id=amzn1.ideas.2RG42J5VNKKTV&ref_=aip_sf_list_spv_ofs_mixed_d_asin Enjoy! Ivan