What does it mean?
B1431 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Side Airbag Rear-Driver Resistance Circuit Short to Ground .
Symptoms
- Airbag warning lamp on constantly and the rear left side airbag switched off
- Fault appears immediately after rear seat, carpet or trim work
- Code is current at every ignition cycle and will not clear
- May be accompanied by other codes from circuits sharing the same loom section
- Nothing else about the vehicle's behaviour changes
Likely causes
- Squib wire pinched between the rear seat frame, the sill or a trim panel and cut through to metal
- Harness trapped when the rear seat cushion or backrest was refitted
- Water in the rear footwell or under the rear seat corroding a terminal until it leaks to the connector shell
- Chafe where the loom passes over a bracket, a floor pan rib or a seat belt anchor bolt
- Internal short to the module housing inside the rear left side airbag unit
- Damaged connector body allowing a pin to touch its metal clip or bracket
- Restraint control module output stage failure
How to fix it
- De-energise the restraint system by switching off, disconnecting the battery and waiting the specified discharge period
- Remove the rear seat cushion and inspect the full run of the yellow harness for pinch marks, cuts and copper showing through
- Check where the loom passes seat belt anchors, floor ribs and trim clips, as these are common cut points
- Look for water in the rear footwell and under the seat, and cure the leak before any electrical repair
- With the airbag unplugged and the approved load tool fitted, check whether the short to ground is still present in the wiring itself
- Repair or renew the damaged harness section and reroute it away from sharp edges and anchor bolts
- Replace the rear left side airbag unit only if the load tool proves the harness is clean, then clear the memory and confirm the lamp goes out