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Home / DTC / B123C — SRS Passenger Airbag Circuit Fault

B123C — SRS Passenger Airbag Circuit Fault

Detailed page for trouble code B123C.

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Code

B123C

LAND ROVER B — Body

SRS Passenger Airbag Circuit Fault

Brand: LAND ROVER
Type: B — Body
Views: UK: 5 EN: 11 RU: 6
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Page language: EN

Causes

  • Open or short in passenger airbag squib wiring/harness
  • Poor/missing connector pin contact at passenger airbag or SRS control module
  • Corroded or damaged harness under passenger seat or in dash
  • Faulty passenger airbag module (squib)
  • Faulty SRS (airbag) control module or connector
  • Faulty occupant classification/seat occupancy sensor or related harness

Symptoms

  • SRS / airbag warning lamp illuminated on instrument panel
  • Passenger airbag disabled message or indicator (may show on dash)
  • Occupant classification/seat belt/PASSENGER AIRBAG indicator abnormal
  • No deployed airbag when code present (if a crash occurs, system may not function correctly)
  • Intermittent SRS lamp (may come and go with seat movement)

What to check

  • Read stored codes and freeze frame data with a compatible diagnostic tool and record all SRS codes
  • Visually inspect passenger airbag connector, wiring harness and under-seat area for damage, chafing or corrosion
  • Check connectors at SRS control module for bent pins, corrosion or loose terminals
  • Confirm state of occupant classification/weight sensor if vehicle uses one
  • Verify battery voltage and ground integrity before and during tests
  • Confirm no recent airbag deployments or improper repairs that could affect circuit integrity

Signal parameters

  • Typical passenger airbag squib resistance: low ohms range (commonly ~0.5–3 ohms) — consult vehicle-specific manual for exact spec
  • Open-circuit: infinite/OL reading between squib terminals or between squib and control module
  • Short-to-ground: near 0 ohms between circuit and chassis ground where not expected
  • SRS power supply: nominal battery voltage present at SRS module supply when key on (check vehicle-specific values)

Diagnostic algorithm

  1. Safety first: follow manufacturer procedures for SRS work. Disable battery and wait the recommended time before disconnecting airbag connectors (consult service manual).
  2. Connect a diagnostic scanner capable of reading SRS/B-codes. Record B123C and any other SRS codes and freeze frame data.
  3. Visually inspect passenger airbag wiring, connectors, and harness routing (under seat, B-pillar, and dash). Look for pin corrosion, broken wires, chafing, or water damage.
  4. With battery disconnected and following safety rules, disconnect passenger airbag connector and measure squib resistance at the airbag connector and at the SRS module harness connector. Compare to manufacturer spec. An open or very high value indicates an open; a near-zero short indicates short-to-ground.
  5. If resistance is within spec, check continuity between airbag connector and SRS module connector for intermittent or high-resistance joints. Wiggle harness and connectors while monitoring for changes.
  6. Inspect and test the occupant classification/seat occupancy sensor and its connector if equipped; faults here can trigger passenger airbag circuit faults or disable the passenger airbag.
  7. Repair or replace damaged wiring, connectors, clips, or the passenger airbag module as required. Replace any repaired connectors using correct crimp/solder and insulation techniques. Protect and secure harness to prevent future chafing.
  8. After repairs, reconnect, re-enable the battery, clear codes with the scan tool, and perform SRS system self-test per manufacturer procedure. Verify lamp extinguishes and code does not return. If code returns, consult vehicle-specific wiring diagrams and consider replacing SRS control module or seeking manufacturer technical service information.
  9. If a deployed airbag is present or any doubt about component integrity exists, replace affected SRS components per OEM requirements. Never reinstall deployed airbag components.

Likely causes

  • Loose or corroded connector at passenger airbag or SRS module
  • Open/short in harness under passenger seat (movement damage)
  • High resistance in squib (airbag) connector or wiring
  • Faulty passenger airbag module

Fault status

⚠️ Status
SRS fault stored: B123C — Passenger airbag circuit fault detected; passenger airbag may be disabled. Service required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.8-2.5 hours

Similar codes

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Defender 300Tdi Years: 1996 Manual in English 7.5 MB
Short description

Official workshop manual for the Land Rover Defender 300Tdi (from 1996 model year). Contains specifications, adjustment, fault diagnosis and step-by-step repair and overhaul procedures for engine, transmission, axles, suspension, brakes, electrical and body. Intended for dealer workshops and trained technicians.

Contents
Key sections:
  • 01 INTRODUCTION
  • 04 GENERAL SPECIFICATION DATA
  • 05 ENGINE TUNING DATA
  • 07 GENERAL FITTING REMINDERS
  • 09 LUBRICANTS, FLUIDS AND CAPACITIES
  • 10 MAINTENANCE
  • 12 ENGINE Tdi
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Workshop Manual Supplement and Body Repair Manual for the Land Rover Defender. Includes general specifications, maintenance schedules, tuning data and step‑by‑step repair procedures for engine, transmission, suspension, brakes, electrical and body repairs. Covers Defender models from 1999 and 2002 model years.

Contents
Key sections:
  • 01 - INTRODUCTION
  • - Introduction
  • - Dimensions
  • - References
  • - Repairs and replacements
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  • - Used engine oil precautions
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  • - Wheels and tyres
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Manual in English Pages: 494 7.1 MB
Short description

Land Rover Range Rover Electrical Library (LRL 0453ENG). Comprehensive manual covering fuse details, earth points, system descriptions, diagnostics and connector pin-outs for electrical troubleshooting and repair. Intended for technicians and service workshops.

Contents
Key sections:
  • 1 INTRODUCTION
  • 1.1 About this document
  • 1.2 Battery voltage
  • 1.3 Electrical precautions
  • 1.4 Battery disconnecting / charging
  • 1.5 Disciplines / greases
  • 1.6 Abbreviations
  • 1.7 HeVAC, sensors abbreviations
  • 1.8 How to use this document
  • 1.9 Connector detail format
  • 1.10 Fault diagnosis
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