B3195

Code

Generic B — Body

Occupant Classification System Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 12 EN: 12 RU: 13

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or corroded seat sensor wiring or connectors (open, short to ground or battery)
Faulty occupant classification sensor (seat mat/load sensor)
Faulty Airbag/OCS control module or related ECU
Poor ground or low reference voltage (fuse, wiring, battery condition)
Water or debris ingress into the seat sensor or connector (after spills or seat repairs)
Incorrectly installed or incompatible aftermarket seat covers or seat heaters interfering with sensor

Symptoms

SRS/AIRBAG warning lamp illuminated on dash
Passenger airbag disabled or OFF indicator active when it should be ON (or vice versa)
Possible stored/active OCS-related DTCs in the airbag/BCM module
Seatbelt reminder or seat-occupied logic behaves incorrectly
Some vehicles may log communication errors on CAN/LIN for the OCS

What to check

Safery first: follow manufacturer SRS procedures (disable battery per service manual) before working on seat/airbag components
Connect a capable scan tool and record all SRS/OCS DTCs and freeze frame data
Visually inspect seat area, connectors, and wiring harness for damage, corrosion or water ingress
Check for related blown fuses and proper battery voltage (key ON)
With a diagnostic tool, view live data for OCS sensor values and compare to expected behavior while seat is occupied and unoccupied
Perform a wiggle test of the seat wiring and connectors while monitoring live data for intermittent changes

Signal parameters

Reference voltage typically supplied to sensor: ~5 V (varies by manufacturer) — verify with service data
Signal output: variable voltage or resistance that changes with load/occupancy; should switch between distinct 'occupied' and 'unoccupied' ranges
Circuit must not be open (infinite resistance) nor shorted to B+ or ground
Some systems communicate occupancy status to the SRS ECU over CAN or LIN messages — check for valid messages on the bus

Diagnostic algorithm

Retrieve and record all diagnostic trouble codes and freeze-frame data with a scan tool; note any additional SRS/OCS codes. 2) Confirm the battery is charged and stable; verify fuses related to SRS/OCS. 3) Visually inspect seat, connectors, wiring harness, and insulation for damage, corrosion, or water entry. 4) Follow safety procedure to disable SRS power (battery disconnect/wait time) before disconnecting connectors or removing seat trim. 5) With ignition ON and using the vehicle wiring diagram, probe the sensor connector: verify reference voltage, ground continuity, and signal presence per service manual. 6) Perform a continuity check from the sensor connector back to the SRS/OCS ECU to detect opens or shorts. 7) Monitor live OCS sensor data while applying a known weight or sitting in the seat to see if signal changes as expected. 8) Perform wiggle tests on harness and connectors while observing live data to find intermittent faults. 9) If wiring and connectors are good and signals out of range, follow service manual to replace the occupant classification sensor/module. 10) After repair or replacement, perform required OCS calibration/relearn per manufacturer procedure. 11) Clear codes and verify repair with a full system scan and road/functional test.

Likely causes

Broken or chafed wiring to the passenger seat OCS sensor
Corroded connector at the seat sensor or ECU
Failed occupant classification sensor module (internal fault)
Loss of 5V reference or signal circuit short to ground

Fault status

⚠️ Status

Occupant Classification System Sensor Circuit Malfunction — the passenger seat occupancy sensor circuit is reporting an invalid, open, shorted, or out-of-range signal; SRS control may disable passenger airbag and will set a warning lamp.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours