What does it mean?
B1728 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Inflatable curtain airbag rear-Passenger resistance circuit short to Ground .
Symptoms
- Airbag warning lamp permanently lit
- Rear passenger-side curtain disabled and will not deploy in a side impact or rollover
- Fault registers as current and returns straight after clearing
- Often shows up after rear trim, headliner or cargo area work, or after water ingress
- Neighbouring SRS circuits in the same loom may set codes at the same time
Likely causes
- Squib wiring rubbed through against the roof rail, C-pillar bracket or belt anchor on the passenger side
- Wire trapped under a trim clip or headliner bracket when the interior was refitted
- Water from a rear seal, tailgate or sunroof drain leak corroding the pillar connector to ground
- Pin pushed back or terminal deformed after disconnecting the curtain connector
- Inflator with an internal short between the squib element and its housing
- Loom cut or crushed during rear body or glass repair
- Restraint control module output shorted internally
How to fix it
- Read and record every SRS code and check whether this one is current
- Ignition off, battery disconnected, wait the manufacturer's stand-down time
- Unplug the curtain squib and install an approved load tool in its place
- Release the module connector and test both squib wires for continuity to ground to prove the short
- Follow the loom along the roof rail and rear pillar, checking clips, brackets and belt anchors for cut insulation
- Check the pillar for water tracks and rust, and fix the leak before repairing wiring
- Repair with SRS repair leads, replace the curtain inflator only if the short is internal, then clear and verify