B10A5 — Front passenger occupancy sensor circuit malfunction

Causes

• Open or short in sensor wiring harness
• Corroded, loose or contaminated connector(s) at the sensor or airbag ECU
• Faulty passenger occupancy sensor mat/module
• Water intrusion or physical damage to the seat sensor mat
• Poor ground or supply voltage to the sensor
• Faulty Supplemental Restraint System (SRS) / Airbag control module or configuration/calibration error

Symptoms

• Passenger airbag enabled or disabled unexpectedly
• Airbag or SRS warning lamp illuminated
• Passenger seat belt/occupant status warning may be incorrect or show 'passenger present' when empty or vice versa
• Diagnostic trouble code B10A5 stored in SRS/BCM memory
• Possible loss of seat belt reminder or incorrect deployment logic for passenger side

What to check

• Perform a full visual inspection of passenger seat, connectors and wiring harness under the seat and along seat tracks
• Check for signs of water damage, seat foam contamination, or aftermarket seat covers that may affect the sensor mat
• Use a scan tool to read B10A5 and related SRS/OCC codes and view live data for the occupancy sensor
• Inspect and tug connectors to expose intermittent faults; look for bent pins, corrosion or foreign material
• Verify power and ground at the sensor connector with ignition on and seat occupant absent/present
• Check related fuses and ground straps for integrity

Signal parameters

• Supply voltage typically 5 V (verify vehicle-specific value) to sensor power pin
• Ground continuity to chassis ground or SRS ground reference
• Occupancy sensor output: varies by design — can be a voltage signal (0–5 V range) or resistance/impedance change when weight applied; expected change should be present when a known weight is applied to the seat
• Idle/unoccupied output: stable baseline (low or mid-level voltage/resistance) with no weight
• Occupied output: clear change in measured voltage or resistance when weight simulating a passenger is applied

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