What NHTSA says the defect is
Mazda North American Operations (Mazda) is recalling certain 2017 CX-5 vehicles equipped with an accessory trailer hitch wiring harness. This harness may be routed such that there is insufficient clearance between the harness and the exhaust muffler, allowing the wiring harness to contact the muffler.
The risk NHTSA states
Contact with the muffler may damage the trailer wiring harness, potentially resulting in the trailer lighting being inoperative, thereby increasing the risk of a crash.
The remedy NHTSA states
Mazda will notify owners, and dealers will reroute the trailer hitch harness away from the muffler, replacing the harness if it is damaged, free of charge. The recall is expected to begin January 20, 2018. Owners may contact Mazda customer service at 1-800-222-5500. Mazda's number for this recall is 1617K.
Campaign 17V744000 · reported to NHTSA 21 November 2017 · Read it on nhtsa.gov →