Not assigned in the generic OBD-II standard - if your scan tool shows this code, it is manufacturer-specific; verify the meaning in your make's service information

U0672 lost communication with Front Control Module is often caused by a blown fuse or a BCM-to-FCM CAN bus short. Start by checking fuses in the underhood fuse box (especially FCM and RAP fuses). Water intrusion into the underhood fuse box is common -- inspect the seal and the fusible links. If power is good, the FCM may need reprogramming at a dealer.

On Ram trucks U0672 typically indicates a CAN-C bus issue between the FCM and the TIPM/BCM. The TIPM under the hood is the known weak point on these trucks. Test resistance between CAN-C high and low pins at the TIPM connector -- should be 60 ohms. If resistance is wrong, TIPM replacement is usually required. Your dealer can confirm whether an open service bulletin or warranty extension applies to your VIN.

Ford U0672 is usually a corroded ground G301 under the driver's dash or water intrusion at the BCM in the left kick panel. Inspect for water stains along the cowl drains -- blocked cowls dump water onto the BCM. Clean/replace ground strap and reseal cowl drains. If BCM is water-damaged, reprogramming with new module is required. Note: this module has to be coded to the vehicle with a factory-level scan tool after installation. Budget for that step, or have a shop supply and code the part.