B1180

Code

Generic B — Body

Passenger Seat Occupant Classification Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 13 EN: 31 RU: 17

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Page language: EN

Causes

Damaged or disconnected seat occupancy sensor (mat or weight sensor)
Faulty sensor module or control unit
Open, short, or corroded wiring and connectors between sensor and restraint control module
Water intrusion or contamination in the seat pad or connector
Poor or intermittent ground or power supply to the sensor
Previous seat repair or aftermarket seat cover interfering with sensor

Symptoms

Illuminated airbag or SRS warning lamp
Passenger airbag status message may show 'OFF' or erratic behavior
Failure to detect passenger occupancy or incorrect occupant classification
Diagnostic trouble code stored (B1180) with possible related codes
Intermittent faults when seat is moved or occupant shifts position

What to check

Read freeze frame and live data with a capable scan tool; note sensor status and any related codes
Visually inspect connectors at passenger seat, under-seat harness, and airbag control module for damage or corrosion
Wiggle the seat and harness while watching live data to detect intermittent changes
Check for signs of water or liquid contamination in the seat cushion and connectors
Measure reference voltage and ground at the sensor connector with ignition on
Measure sensor output voltage or resistance per manufacturer procedure

Signal parameters

Typical sensor reference supply: approx. 5 V (varies by manufacturer) — verify manufacturer spec
Sensor output: varies with occupant weight; often a duty cycle, voltage (0–5 V) or resistance range — should be stable and change with load
Expected open-circuit: infinite resistance or open; short to ground or battery is a fault
Intermittent signal or frequent rapid changes indicate wiring or connector issues
Scan tool classification states: 'Empty', 'Child', 'Adult', or 'Error' (labels vary by vehicle)

Diagnostic algorithm

Use a scan tool to confirm B1180 is current or stored and record any other SRS codes.
Inspect the passenger seat area: connectors, harness routing, seat bottom pad and covers for damage, moisture, or aftermarket interference.
With battery connected and ignition ON (follow safety procedures for SRS systems), monitor live OCS data while an assistant sits, shifts weight, or the seat is moved. Note changes and any dropouts.
Back-probe the sensor connector and verify reference voltage and ground continuity to the airbag control module. Repair poor grounds/power as needed.
Measure sensor output (voltage or resistance) at rest and while applying weight; compare to spec or look for open/short conditions. Replace sensor if output is out of expected behavior and wiring is good.
If wiring or connector damage is found, repair or replace the harness and retest. Use manufacturer-approved splice/repair methods and protect wiring from seat movement.
After repairs, clear codes and perform system checks with a scan tool. Confirm no recurrence of B1180 and correct passenger airbag status under various seating conditions.
If fault persists and wiring checks good, replace the occupant classification sensor/module per manufacturer instructions and retest.

Likely causes

Connector loose, pushed out, or corroded at the seat or floor harness
Damaged wiring harness under the seat (pinched by seat rails, worn insulation)
Failed occupant classification sensor pad or internal circuit
Water or liquid spilled on the seat causing sensor failure
Low or missing reference voltage or ground at the sensor connector

Fault status

⚠️ Status

Malfunction detected in passenger seat occupant classification sensor circuit (open/short/intermittent/out-of-range). May disable or alter passenger airbag deployment logic.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours