The mat may be faulty causing a faulty reading in weight. There is a recall for this but I did not see a fault code reading for your concern. Here is what the recall says:
2008 Hyundai Sonata
Recall 08V161000: Air Bag System Defect
Vehicle Restraints and Safety Systems Technical Service Bulletins Recall 08V161000: Air Bag System Defect
RECALL 08V161000: AIR BAG SYSTEM DEFECT
MAKE/MODELS: MODEL/BUILD YEARS:
MANUFACTURER : Hyundai-KIA America Technical Center Inc.
MFR'S REPORT DATE: April 01, 2008
NHTSA CAMPAIGN ID NUMBER: 08V161000
NHTSA ACTION NUMBER: N/A
COMPONENT: Air Bags
POTENTIAL NUMBER OF UNITS AFFECTED: 393714
Hyundai is recalling 393,714 M/Y 2006-2008 Sonata vehicles equipped with an advanced air bag system which features an Occupant Classification System (OCS) in the right front seat. The purpose of the OCS is to disable the right passenger seat front air bag when it detects the presence of a child restraint system or small child in the right front seat. The right front air bag is disabled to prevent injuries to a child that may result from a right front air bag inflation during a crash.
Misclassification of a small stature adult as a child in the right front passenger seat may cause the right front air bag to not inflate in an accident that merits air bag deployment and may result in injury to the right front occupant.
Dealers will verify that the OCS does not properly recognize a properly seated adult occupant. After verification, dealers will remove the right front seat cushion assembly and ship it to an evaluation and repair facility. This facility will evaluate and repair or reprogram the seat cushion and OCS as necessary. The recall is expected to begin on or about May 26, 2008. Owners may contact Hyundai at 1-800-633-5151.
Hyundai recall No. 083. Customers may contact The National Highway Traffic Safety Administration's Vehicle Safety Hotline at 1-888-327-4236 (TTY: 1-800-424-9153); or go to http://www.safercar.gov.
If the recall was already done then as you stated earlier with an internal fault, the mat can have an internal fault. In this case the mat would need to be replaced and calibrated. The calibration would need to be done at the dealership or a specialized independent Huundai repair shop. Call the number listed and have the VIN# ready to verify if the recall applies.
Tuesday, May 28th, 2019 AT 11:36 PM