What does it mean?
B1908 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Rear sensor PWM signal fault .
Symptoms
- Air bag warning lamp on continuously
- Rear impact protection, side curtain bags and rear belt pretensioners may all be inhibited
- Fault often follows a wet boot floor or a rear end knock
- Code may set intermittently over bumps and rough surfaces
- Restraint system warning message on the information display
Likely causes
- Water in the rear sensor connector after a boot seal, tail lamp gasket or rear screen leak
- Sensor internal electronics failed, so the duty cycle it transmits is wrong
- Harness chafed inside the quarter panel or C pillar where the loom passes a metal edge
- Sensor mounting bolt loose or bracket deformed after rear body repair
- Poor sensor supply voltage or a corroded ground point in the rear of the vehicle
- Damage during subwoofer, trailer wiring, camera or alarm installation in the rear
- Restraint control module input circuit fault
How to fix it
- Apply air bag safety procedure before disconnecting any restraint component
- Read the codes with freeze frame and check the boot and rear footwells for water
- Inspect the rear sensor connector for moisture and corrosion, dry it thoroughly and reassess before parts are replaced
- Check the sensor mounting is tight and the bracket is not deformed, as signal quality depends on solid mounting
- Measure supply voltage and ground at the sensor connector and check the signal wire for continuity and shorts
- Cure the water leak that caused the corrosion before completing the repair
- Treat the restraint control module as the last step after wiring, ground and sensor have all been proven