The recall documentation states that the two sensors in the side curtain airbag system, which detect rollover, can fail. If one sensor fails, an airbag warning light will illuminate and the roll detection system will be disabled.
If both sensors fail at the same time, the curtain airbags, as well as the seatbelt pretensioners may activate inadvertently. This may lead to serious injury to those inside the vehicle.
Toyota is replacing these substandard sensors with improved sensors free of charge. Toyota is contacting all affected customers, but you can reach Toyota at 1-800-331-4331 if you feel your 2008 Highlander is affected, or you need more information.
[NHTSA Recall Report]