Code
B1431
MITSUBISHI
B — Body
FL side ABG squib open
Views:
UK: 15
EN: 16
RU: 10
AI status
Completed
Completed
100%
Causes
- Disconnected or loose connector at the front-left airbag module or harness
- Broken/open wiring in harness (common at door hinge, seat base or under trim)
- Damaged or failed squib (airbag igniter) inside the airbag module
- Corroded terminals or poor crimp at connector
- Improper repair after prior deployment (cut/incorrectly spliced wiring)
- Faulty SRS/airbag control module or internal open circuit
Symptoms
- Airbag/SRS warning light illuminated on instrument panel
- Stored B1431 DTC (may be accompanied by other SRS codes)
- Front-left airbag may be inhibited (possible non-deployment of that airbag)
- Related restraint features (seatbelt pretensioner) may be disabled or show faults
- Vehicle may show reduced safety functionality until the fault is cleared and repaired
What to check
- Read and record all stored SRS codes and freeze-frame data with a qualified scan tool
- Visually inspect connectors and wiring at the front-left airbag, seat base, door hinge and related harness routing
- Check for evidence of prior deployment or poor repairs (splices, tape, burned connectors)
- Confirm occupant classification/seat sensor wiring is intact if applicable
- Measure continuity and resistance of the squib circuit using proper SRS-safe procedures
Signal parameters
- Squib circuit resistance: typically a low-ohm value (commonly around 1–5 ohms on many systems); an open circuit reads infinite/OL
- Ignition ON supply voltage present at SRS ECU connector (~12 V) — only for reference; no deployment voltage should be present
- No continuity (open) between squib terminals indicates open circuit
- Short to battery or ground would show near-zero ohms; B1431 indicates open rather than short
Diagnostic algorithm
- Safety first: follow manufacturer SRS procedures. Disable the SRS system by switching off ignition, disconnecting the battery negative, and waiting the manufacturer-specified time before touching airbag connectors or wiring.
- Use a capable scan tool to read the SRS module. Note all codes, clear them, then re-scan to confirm B1431 returns and to catch any additional faults.
- Visually inspect the FL airbag module connector, wiring harness, and associated routing (seat base, door hinge, under-dash). Look for unplugged connectors, pin damage, corrosion, or crushed wiring.
- With SRS system made safe per manufacturer instructions, disconnect the connector at the FL squib and measure resistance across the squib terminals. A healthy squib typically shows low resistance (approx. 1–5 ohms). An open-circuit is indicated by infinite/OL.
- If squib shows open, perform continuity checks back to the SRS control module connector. Isolate wiring sections (seat plugs, door jamb plugs) and check continuity segment-by-segment to locate the open.
- If wiring and connectors are good and continuity is open only at the squib, suspect a failed squib/airbag module. Replace the airbag module following manufacturer procedures.
- If a wiring repair is required, repair using correct automotive-grade connectors, crimps, and insulation; avoid splicing through areas that flex. After repair, reconnect, clear codes and perform SRS system self-test and verification drive or tool checks per manufacturer.
- If DTC persists after wiring and module replacement, consider SRS control module fault and consult manufacturer diagnostics or replace per factory procedure.
Likely causes
- Connector at the FL airbag module is unplugged or has a poor contact
- Wire break in harness where it flexes (door hinge, seat slide track)
- Failed squib inside the airbag module requiring module replacement
- Corroded connector terminals or bent pins
- Clock spring failure (if the FL squib route includes steering wheel circuitry)
Fault status
Status
Open circuit detected in front-left airbag (squib) circuit. The SRS control unit has lost continuity to the FL squib; the airbag may be disabled until the circuit is repaired.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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