General Motors has decided that a defect relating to vehicle safety exists in certain 2021 model year Buick, Cadillac, Chevrolet and GMC vehicles.

In April 2021, a Problem Resolution and Tracking System (PRTS) issue was opened following validation testing for a future model year vehicles, where it was noted some conditions in which loss of communication with the sensing diagnostic module (SDM) did not illuminate the airbag malfunction indicator lamp. GM opened an investigation in May 2021. A review of field data showed 19 warranty claims possibly linked to this condition.

According to the defect report, a software problem exists in some of these vehicles which would cause a SDM communications fault to illuminate the airbag malfunction indicator lamp, but only on alternating ignition cycles. As a result, an SDM communications fault would not consistently illuminate the airbag light on every ignition cycle to indicate a problem to the driver.

A driver might not be warned of an SDM loss of communication fault which might indicate a problem with airbag deployment. If airbags do not deploy appropriately in a crash, there is an increased risk of injury.

Description of the Cause : The Communications Gateway Module, also referred to as the serial data gateway module, software does not correctly store data indicating loss of communication with the SDM.

GM dealers will correct the problem by updating the software for the communications gateway module. Owner notification letters are expected to be mailed in July 2021. GM’s number for this recall is N212338110 and the NHTSA campaign number is 21V-421.