B111B

Code

Generic B — Body

Front driver seat occupant sensor circuit malfunction

Brand: Generic

Type: B — Body

Views: UK: 27 EN: 26 RU: 23

AI status

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Page language: EN

Causes

Damaged or shorted wiring harness to the driver seat occupant sensor
Poor connector contact, corrosion or bent pins at the seat harness or SRS module
Faulty occupant sensor mat (resistive, capacitive pad or load cell)
Water intrusion into seat cushion or sensor assembly
Faulty seat control module or SRS/airbag control unit
Aftermarket seat covers or heater elements interfering with sensor operation

Symptoms

SRS/airbag warning lamp illuminated (airbag system fault)
Passenger/driver airbag enabled/disabled incorrectly or message about occupant classification
Seat belt reminder or chime behavior may be incorrect
Occupant detection inconsistent (detects occupant when seat is empty or fails to detect occupant)
Possible inability to arm/disarm airbag for that seating position

What to check

Read and record all stored SRS and body control module fault codes and freeze frame data with a capable scan tool
Visually inspect seat, underside, and wiring harness for damaged insulation, chafing, or pinched wires
Check connectors under the seat for corrosion, bent pins, water, or loose terminals
Confirm no aftermarket seat covers or heaters are installed that might affect sensor operation
Scan live data for occupant sensor values (resistance, capacitance, raw counts, or status flags) and observe behavior while sitting, leaving or shifting weight on the seat
Perform a wiggle test on the harness while monitoring live data or DTCs to look for intermittent faults

Signal parameters

Sensor type may be resistive, capacitive or load‑cell based — many systems report raw counts, resistance (ohms), or a 0–5 V analog signal to the SRS ECU
Expected idle/unoccupied values: sensor reports ‘empty’ state (high resistance/low capacitance or specific low raw count) — refer to OEM spec for exact numbers
Expected occupied values: significant change from empty state (lower/higher resistance or different raw count/voltage) when a person sits
Power supply to sensor typically 5 V or vehicle battery via module; ground should be continuous
Communication: some systems report occupancy over SRS or body CAN/LIN — check for periodic messages and no bus errors

Diagnostic algorithm

Connect a professional scan tool that supports SRS/occupant classification and read all codes and freeze frame data
Document the exact conditions when the code set (weight, seat position, installation of accessories)
Inspect wiring and connectors under the driver seat for damage, corrosion, water, or loose terminals; repair any damage and retest
With ignition on, monitor occupant sensor raw data or status while performing simple tests: empty seat, sit centrally, shift weight side‑to‑side. Note if values change as expected
Perform a wiggle test on the seat harness while monitoring live data and watch for changes or returned DTCs—if DTCs appear, isolate and repair the wiring/harness
Measure sensor circuit resistance or voltage at the seat sensor connector per OEM procedure; compare to specifications (if unknown, compare left/right seat if passenger sensor exists)
If wiring and connectors are good but sensor values do not change correctly, remove seat and bench‑test the sensor mat/module if possible or replace with known good unit
After repair or replacement, clear codes, perform occupant classification calibration or SRS system relearn per service manual, then verify no reoccurrence of code and proper airbag enable/disable behavior
If multiple sensors or modules report faults or bus communication errors persist, test/replace the SRS/airbag control unit only after confirming all seat-side repairs and configuration steps are complete
Record final results and advise customer of repairs performed and any necessary follow-up monitoring

Likely causes

Wiring abrasion at seat base or under carpet causing intermittent short/open
Connector corrosion at plug under the seat
Torn or crushed sensor mat from previous seat repair or impact
Water/moisture contaminated sensor area causing changed resistance/capacitance
Faulty or failed occupant sensor module (sensor electronics)

Fault status

⚠️ Status

B111B — Front driver seat occupant sensor circuit malfunction. SRS/Airbag system has detected an out‑of‑range or intermittent signal from the driver seat occupancy sensor. May disable/affect airbag/occupant classification for that seat and set SRS warning lamp.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours