B116C

Code

Generic B — Body

Occupant Classification System (OCS) Sensor Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 13 EN: 19 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed wiring in seat harness
Corroded or loose connector terminals
Water/moisture intrusion into seat cushion or connector
Failed occupant classification sensor or sensor module
Faulty airbag/SRS control module
Poor ground or power supply to the sensor

Symptoms

SRS/Airbag warning lamp illuminated
Passenger airbag status message may indicate disabled/not available
Passenger presence detection incorrect (airbag on/off when seat occupied/vacant)
Seat belt reminder or other occupant-detection related warnings
Possible diagnostic trouble codes stored for OCS and related circuits

What to check

Read recorded DTC(s) and freeze-frame data with a capable scan tool; note related codes.
Visually inspect passenger seat area, connectors under seat, and seat track for damage or water.
Inspect seat wiring harness for chafing, broken strands, or pinched sections where it passes through the seat frame.
Check connectors for corrosion, bent pins, or poor mating; reseat and inspect terminal fit.
Backprobe connector and measure reference voltage, ground, and sensor signal with ignition on (follow safety procedures).
Perform a wiggle test of the seat harness while monitoring live data for intermittent changes.

Signal parameters

Reference supply: typically a regulated 5 V or vehicle-specific reference (verify in service literature)
Sensor signal: usually an analog voltage or resistance that changes with occupancy — expected 0–5 V range or manufacturer-specific values
Ground continuity: near 0 ohms between sensor ground and chassis ground
Open-circuit: infinite resistance between signal and module pins indicates open wiring
Short-circuit: near 0 ohms between signal and battery positive/ground indicates short
Digital/serial: some OCS modules use LIN/CAN or module-to-module messaging — check for communication frames if applicable

Diagnostic algorithm

Safety first — follow the vehicle manufacturer's SRS service procedures before working around the seat/airbag system (disable SRS power per service manual).
Use a scan tool to read DTC B116C and any related codes; record freeze-frame and live data for the OCS sensor (signal voltage/resistance and status).
Visually inspect the passenger seat cushion, connectors under the seat, and the entire seat harness routing for damage, water, or pinched wires.
With SRS power enabled per safe procedures, backprobe the sensor connector: confirm reference voltage and ground at the connector with the ignition on and key off as specified. Compare values to service specs.
Monitor the sensor signal while seat is unoccupied and while a test weight or occupant is present. Look for plausible, stable changes and no large jumps or dropouts.
Perform continuity and resistance checks between the sensor connector and the SRS control module connector with the battery disconnected. Repair any opens, shorts, or high-resistance joints.
Inspect and, if necessary, repair or replace corroded terminals, damaged wiring, or harness sections. Protect repaired wiring from chafing and routing issues.
If wiring and connectors are good, consider replacing the occupant classification sensor/module per manufacturer procedure. Some vehicles require calibrated replacement sensors — perform required calibration or learning procedure.
After repairs, clear codes, perform required OCS initialization/calibration, and verify proper system behavior and no recurrence of the code.
If the fault persists, check the SRS/airbag control module and vehicle software bulletins; module reprogramming or replacement may be required.

Likely causes

Open or shorted signal/return wiring between sensor and SRS module
Lost reference voltage (no 5 V or other supply) to sensor
Intermittent connector contact due to corrosion or pin damage
Sensor internal electronics failed (short/open/unstable output)
Water intrusion in seat cushion causing sensor malfunction

Fault status

⚠️ Status

OCS sensor circuit fault detected. Possible open/short/intermittent or communication error in the occupant classification sensor circuit. Passenger airbag enable/disable may be affected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.5 hours