Five months after federal regulators opened a probe into airbag mats that fail to detect when a child is present in the front seat of certain Kia sedans, the agency announced it would close the investigation without seeking a recall of the affected vehicles. 

The National Highway Traffic Safety Administration shut the door on the months-long investigation into a potential malfunction of the front passenger side airbag occupant classification system (OCS) in 186,000 model year 2007 to 2009 Kia Spectra vehicles after the carmaker extended the warranty on the sensor mat.

Regulators opened the probe into the issue in September after receiving 163 complaints from consumers that the passenger side airbag did not operate as intended.

According to a notice [PDF] from NHTSA, the front seat passenger occupant classification system sensor mat, which is embedded in the passenger seat cushion and intended to detect a child or small stature occupant who could be injured by deployment of the airbag, may fail.

The OCS may develop a failure due to an open circuit in the sensor mat caused by the mat cracking during use.

“A trouble code will then be stored in the air bag control unit and the air bag warning light will be illuminated,” NHTSA says in its notice [PDF]. “If this fault is detected, the OCS will not suppress the front passenger air bag and in a crash of sufficient severity the front passenger air bag will deploy regardless of the nature or size of the child seat or occupant in the front passenger seat.”

NHTSA determined that the relatively low complaint rate, and Kia’s decision to implement an extended warranty program — allowing free sensor mat replacement for 15 years — was enough to close the investigation.

The Office of Defects Investigation “has tentatively concluded that the actions taken by Kia mitigate any unreasonable risk to safety posed by OCS sensor mat failures in the subject vehicles.”

Kia will notify owners about the warranty and send them to dealers if a warning light comes on.

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