B1072

Code

Generic B — Body

Occupant classification sensor circuit fault

Brand: Generic

Type: B — Body

Views: UK: 15 EN: 22 RU: 19

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Page language: EN

Causes

Open, short-to-ground, or short-to-voltage in OCS wiring or connectors
Corroded, loose, or damaged seat connector(s)
Failed occupant classification sensor (mat/pad) or its internal electronics
Water intrusion or contamination of the sensor/mat
Faulty SRS/airbag control module or loss of communication
Recent seat repair, replacement, or aftermarket seat cover interfering with sensor

Symptoms

Airbag or SRS warning lamp illuminated on dash
Passenger airbag status message may read 'Passenger Airbag Off' or 'System Fault' incorrectly
Passenger presence/weight detection unavailable or inconsistent
Failure to complete occupant classification calibration or learn procedure
Related SRS faults or communication errors stored in airbag module

What to check

Scan vehicle with a compatible SRS diagnostic tool. Record all airbag/OCS-related codes and freeze-frame data.
Inspect seat area for water, debris, damaged padding, or aftermarket covers.
Visually inspect and reseat connectors under passenger seat and at the airbag control unit. Check for corrosion, bent pins, or moisture.
Check battery voltage and chassis grounds; ensure stable power during testing.
Perform wiggle test on seat wiring while monitoring live data to reproduce fault.
Measure reference supply and ground at the OCS connector and compare to expected values.

Signal parameters

Reference supply: typically 5 V or regulated reference (check vehicle-specific service data).
Ground: near 0 V with good continuity to chassis ground.
Sensor output: variable voltage or resistance that changes with applied load; should change between empty seat and occupied conditions.
Open-circuit indication: very high resistance (megaohm) or no signal.
Short-circuit indication: near 0 Ω or signal rail voltage present continuously.
CAN/serial comm: airbag module should communicate over vehicle CAN; check bus idle voltages (~2.5 V) and presence of related messages if applicable.

Diagnostic algorithm

Read and record all DTCs and freeze frame data with a capable SRS scan tool. Note any other related codes.
Verify battery state-of-charge and secure a stable power source; clear codes and attempt to re-run to see if code returns.
Perform a visual inspection of the passenger seat, seat rails, connectors under the seat, and sensor mat for physical damage or moisture.
Disconnect connector(s) and inspect pins for corrosion, bending, or pushed-out terminals. Clean and repair as required.
With the ignition on, measure reference voltage and ground at the OCS connector. Compare to factory specs. If no reference, trace supply fuse, relays, and wiring.
Measure sensor circuit resistance/voltage while seat is empty and while a known test weight is placed on the occupant area (use manufacturer guidance). Verify the signal changes and falls within specified ranges.
Wiggle the harness and operate the seat through its full travel while monitoring live data and DTCs to identify intermittent wiring faults.
If wiring and connectors are good but sensor readings are out of range or unresponsive, replace the occupant classification sensor/mat per manufacturer procedure.
If replacement is performed or if module communication was interrupted, perform the required OCS calibration/learn and SRS system resets following OEM instructions.
Clear DTCs, recheck with scan tool, and perform verification steps (power cycle, self-tests, road test if required). If code persists, consider SRS control module fault and consult manufacturer diagnostics.

Likely causes

Damaged wiring harness under the seat (pinched by seat rails or broken from movement)
Connector backshell pushed out or pins bent/corroded at the sensor or module
Sensor mat damaged (puncture, moisture) or internal header failure
Seat cushion or cover improperly refitted after service altering sensor readings
Faulty occupant classification module (internal electronics failure)
Short in sensor circuit caused by spilled liquid or rusted contacts