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Home / DTC / B1B73 — Side impact sensor(LH) 2

B1B73 — Side impact sensor(LH) 2

Detailed page for trouble code B1B73.

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B1B73

MITSUBISHI B — Body

Side impact sensor(LH) 2

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or shorted sensor wiring harness (open circuit, short to ground or battery, chafing)
  • Corroded/loose connector at the side impact sensor
  • Faulty side impact sensor (internal fault or degraded element)
  • Faulty airbag control module (rare)
  • Water intrusion or contamination at connector or sensor
  • Damage or misalignment from previous collision or repair

Symptoms

  • SRS / airbag warning lamp illuminated on instrument panel
  • Possible disablement of left side airbag and/or seat belt pretensioner
  • Multiple related SRS codes present (indicating communication or multiple sensor faults)
  • Vehicle may fail safety inspection with active SRS fault

What to check

  • Read and record all SRS-related codes and freeze-frame data with an SRS-capable scan tool
  • Visually inspect LH side impact sensor, its mounting and connector for damage, water intrusion or corrosion
  • Inspect wiring harness routing from sensor to airbag control module for chafing, pinches or repair splices
  • With battery connected and ignition ON, check for proper reference power and ground at the sensor connector (use manufacturer-specified safe procedures)
  • Perform a wiggle test on wiring/connectors while monitoring live sensor data for intermittent changes
  • Measure sensor signal voltage (or resistance where specified) and compare to factory specification

Signal parameters

  • Refer to factory service manual for exact values. Typical parameters to expect (verify before use):
  • Reference/supply voltage: usually a regulated reference (often 5 V) present at the sensor connector with ignition ON
  • Signal output at rest: commonly near mid-supply (example ≈2.5 V) — an impact produces a transient excursion
  • Ground: good chassis/ECU ground continuity required
  • Resistance/impedance: sensor element/diagnostic pins may show manufacturer-specified resistance; open or short indicates fault
  • Note: exact voltages, pinouts and test methods vary by model/year — always confirm with Mitsubishi service data

Diagnostic algorithm

  1. Safety first — follow Mitsubishi procedures for SRS work: disable the battery and wait the specified time before disconnecting connectors. Use an SRS-capable scan tool for diagnosis and clearing codes.
  2. Read all SRS codes and note freeze-frame. Check for other related codes (other side sensors, main ECU faults).
  3. Perform a visual inspection of LH side impact sensor, connector, harness and mounting. Look for bent pins, corrosion, water ingress or signs of impact.
  4. Reconnect battery (if required for live tests) and with scan tool monitor live data for the LH side impact sensor. Observe if the sensor reports reasonable rest values and if value changes during a light, controlled functional tap test per factory instructions.
  5. With ignition ON, verify reference voltage and ground at the sensor connector pins per factory pinout. Compare measured voltages to service data. Look for open circuits or shorts to ground/battery.
  6. If voltages are out of range or intermittent, perform continuity/resistance checks between sensor connector and airbag control module connector to isolate wiring fault. Repair any damaged wiring or connector pins.
  7. If wiring and connectors are good, replace the side impact sensor with a new OEM or approved unit and re-test. Ensure sensor mounting torque and orientation match specification.
  8. If New sensor does not clear fault, inspect airbag control module connections and consider module diagnostic/repair per factory guidance. Avoid replacing module without proper confirmation.
  9. Clear codes with scan tool and perform full SRS system check. Confirm no return of B1B73 and verify system status.
  10. After repair, follow any required SRS system initialization or calibration procedures mandated by Mitsubishi.

Likely causes

  • Connector corrosion or poor pin contact at LH side impact sensor
  • Open or short in sensor signal or power/ground circuit between sensor and airbag control module
  • Failed side impact sensor due to age, impact or water damage
  • Improper sensor mounting or mechanical damage after a collision repair

Fault status

⚠️ Status
SRS: Side impact sensor (LH) #2 signal fault — open/short/intermittent. Airbag system requires inspection and repair.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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