B116B

Code

Generic B — Body

Passenger Seat Occupant Classification System Fault

Brand: Generic

Type: B — Body

Views: UK: 0 EN: 4 RU: 0

AI status

Completed

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Page language: EN

Causes

Loose, corroded, or damaged connector/pigtail at seat sensors or OCS module
Open or shorted wiring in seat harness (water intrusion, chafing)
Faulty occupant classification sensor/mat or pressure/capacitance sensor
Failed occupant classification module or airbag control module
Seat cushion or aftermarket seat cover/mat interfering with sensor readings
Incorrect calibration or corrupted software in OCS/airbag module

Symptoms

Airbag warning light illuminated on dash
Passenger airbag disabled message or indicator
Inability to register occupant presence — passenger airbag may remain off
Intermittent warning depending on seat position or occupant movement
Stored DTC(s) related to passenger classification or seat sensors

What to check

Read and record all stored DTCs and freeze frame data with a capable scan tool
Perform an initial visual inspection of the passenger seat, connectors, and harness for damage or corrosion
Verify there are no aftermarket seat covers, cushions, or objects on the seat affecting the sensors
Check for signs of water intrusion or fluid spills in and under the seat
Confirm proper seating of connectors at the OCS/airbag control module and seat module
Run an OCS/airbag system self-test or diagnostics if available

Signal parameters

Sensor output: variable voltage or resistance that changes when weight/load is applied (expected to change smoothly with load)
Continuity: no open circuits between seat sensors and module; measure resistance/continuity per service manual
Communication: OCS/seat module messages present on vehicle bus (CAN/lin); module should respond to diagnostic requests
Power/ground: stable 12 V supply to OCS/seat module when ignition is ON and good chassis ground
Fault codes: DTC stored with timestamps or freeze-frame indicating when fault occurred

Diagnostic algorithm

Connect a diagnostic scan tool and record all passenger airbag/OCS DTCs and freeze frame data.
If DTC is stored as current or pending, note whether it is permanent/intermittent and attempt to reproduce by having a test occupant sit in different positions.
Visually inspect the passenger seat area for damage, foreign objects, aftermarket accessories, spills, or wetness. Remove seat covers and test again.
Inspect connectors under the seat and at the OCS/airbag control module; disconnect and reseat connectors, inspect for corrosion, bent pins or water intrusion.
Perform a wiggle test: with ignition ON, monitor the OCS sensor data or DTC status while gently moving the seat and harness to identify intermittent wiring faults.
Measure power and ground at the OCS/seat module connector; verify specified supply voltage and a solid ground.
Measure sensor outputs (voltage/resistance) at the sensor harness and compare the change when weight is applied. Follow the vehicle manufacturer service manual for exact test values and procedures.
Check data bus communication to the OCS module using the scan tool. If the module is not responding, inspect CAN/LIN wiring and termination.
If wiring and connectors are good but sensor readings are out of spec, replace the occupant classification mat/sensor assembly per manufacturer instructions.
If sensor and mat replacement did not correct the issue, consider module replacement or reflashing software as specified by the manufacturer. After repair, clear codes and perform the required OCS calibration/initialization procedure and confirm the system returns to normal operation.
If fault persists or is intermittent, consult manufacturer technical service bulletins (TSBs) and wiring diagrams, and consider bench-testing the module or seeking manufacturer-level diagnostic support.

Likely causes

Moisture damage to seat sensor connectors or mat
Broken wire in seat harness near the seat base (common wear point)
Defective occupant detection mat under the seat cushion
Connector not fully seated after seat removal/repair
Faulty OCS module or poor CAN/serial communication to the airbag module

Fault status

⚠️ Status

Passenger seat occupant classification fault detected. The system may disable the passenger airbag and illuminate the airbag warning light. Fault can be current, intermittent, or historical; further electrical and component testing is required before repair.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours