B1185

Code

Generic B — Body

Front Passenger Occupant Sensor Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 17 EN: 22 RU: 17

AI status

Completed

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Page language: EN

Causes

Open or shorted wiring in the occupant sensor harness
Poor or corroded connector at the seat/occupant classification module
Damaged occupant sensor mat or sensor element under the passenger seat
Water/moisture contamination of the seat or sensor connector
Interference or short from aftermarket seat heaters or accessories
Faulty occupant classification module (OCM) or SRS control module

Symptoms

SRS / airbag warning lamp illuminated on the dash
Passenger airbag OFF indicator behaves incorrectly (may be disabled when occupied or enabled when empty)
Vehicle stores B1185 (and possibly related B1xx codes)
Possible inability to enable/disable passenger airbag as expected
Diagnostic trouble codes return after clearing if fault persists

What to check

Read and record all SRS codes and freeze-frame data with a capable scan tool
Visually inspect passenger seat, connectors and harnesses for damage, corrosion or water
Check for recent seat removal or collisions that could have damaged sensors/wiring
Verify software and calibration are up to date per manufacturer service information
Check for interaction from aftermarket items (seat covers, heaters) and remove if present

Signal parameters

Reference supply typically from vehicle SRS module (commonly low-voltage 5 V reference) — verify in vehicle-specific manual
Sensor output typically an analog or discreet signal within 0–5 V range to the occupant classification module
Continuity across mat elements: expected finite resistance when intact; open circuit if broken
Data/communication between occupant classification module and SRS may use a low-speed serial link on some vehicles — check for communication errors
Pin count and exact voltages vary by make/model; always confirm with wiring diagram

Diagnostic algorithm

Retrieve and record all SRS/airbag codes and freeze frame information with a qualified scan tool.
Follow vehicle manufacturer SRS safety procedures: disable battery/airbag system as specified before working on seat wiring or sensors.
Visually inspect passenger seat area, under-seat connectors and wiring for damage, corrosion, disconnected plugs, or water ingress.
Reconnect any loose connectors and secure harnesses; clean corroded terminals and apply dielectric grease if specified.
With SRS power enabled per service manual and using a scan tool, monitor occupant sensor live data while a known-weight test (or a person) sits in the seat; observe for expected signal change.
Perform continuity and resistance checks on occupant sensor mat circuits (per wiring diagram). Look for opens, shorts-to-ground or shorts-to-power. Wiggle harness while monitoring live data to find intermittent faults.
Inspect for interference from aftermarket seat heaters or accessories; remove/disable and retest.
If wiring and connectors pass, test or swap occupant classification module if vehicle-specific procedures allow, or bench-test the sensor mat per service literature.
Repair or replace damaged wiring, connectors or sensor mat. Replace occupant classification module only if confirmed faulty and after following programming/relearning procedures required by manufacturer.
Clear codes, perform required system resets/relearns, and verify by driving and re-scanning that the fault does not return.

Likely causes

Disconnected or loose connector under the passenger seat
Damaged wiring where it passes between seat and body (pinch point)
Failed sensor mat (insulation break or element open)
Moisture intrusion in seat cushion or connector
Faulty occupant classification module or SRS control module

Fault status

⚠️ Status

Front passenger occupant sensor circuit fault detected. SRS/airbag control module has logged a fault that may affect passenger airbag enable/disable function.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours