What does it mean?
B1418 is a Body (airbags, seat belts, body electronics) fault code. It indicates: SIS (Side Impact Sensor) Rear-Driver Defect .
Symptoms
- Airbag warning lamp remains lit after the initial bulb check
- Rear left side and curtain airbag protection is switched off
- The code stays current no matter how many times it is cleared
- Fault may first appear after heavy rain, a car wash or a flooded footwell
- No noise, no performance change, only the warning lamp
Likely causes
- Internal electronics or accelerometer failure inside the sensor unit
- Water damage from a leaking rear door seal, sill or wheel arch reaching the sensor housing
- Sensor previously subjected to an impact, or reused from a vehicle that had been in a collision
- Sensor housing cracked or distorted by over torqued mounting bolts
- Long term corrosion at the sensor connector affecting its internal supply
- Low system voltage or a weak battery causing repeated self test failures
- Restraint control module misjudging an otherwise healthy sensor
How to fix it
- Turn the ignition off, disconnect the battery and wait the required discharge time before working on the system
- Check the battery state of charge and system voltage, since a weak supply can make sensors fail their self test
- Lift the rear left sill trim, look for damp carpet or water staining and repair the leak before fitting parts
- Inspect the sensor connector for corrosion, green pins and secure latching
- Check the mounting bolts are tight to specification and the sensor body is not cracked or deformed
- Swap the sensor with the matching unit on the other side where part numbers allow and see whether the fault follows the sensor
- Fit a new correct sensor, carry out any configuration required, clear the codes and verify the lamp goes out