Water can damage the weight sensor in the front, passenger seat, causing the SRS (airbag) light to illuminate. There is an electrical component in the seat cushion susceptible to fluid damage. Any spills should be dried up immediately in order to try and prevent damage to the sensor.
Car Problem Reports
Mercedes-Benz E350 SRS Light Due to Water Damage On Passenger Seat Weight Sensor
Mercedes-Benz E350 Problem
Average Mileage: 80,150 mi (68,000 mi - 92,300 mi)
Visitor, 2006 Mercedes-Benz E350, 68,000 mi
Weight Sensor on front passenger seat illuminated due to water damage.