B10B4

Code

Generic B — Body

Passenger seat occupancy sensor circuit - performance

Brand: Generic

Type: B — Body

Views: UK: 8 EN: 24 RU: 17

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed wiring in seat harness
Loose, corroded or pushed-back connector(s) at seat sensor or module
Failed or degraded occupancy sensor (pressure pad, mat sensor, or capacitive element)
Poor ground or lost reference voltage to the sensor circuit
Water intrusion or contamination in the sensor/seat cushion
Interference from aftermarket equipment (heaters, electronics)

Symptoms

Passenger airbag enable/disable light illuminated or flashing
Passenger occupant detection status incorrect (airbag on when seat empty or off when occupied)
Airbag warning lamp or seatbelt/airbag system message on dash
Seatbelt reminder behaves unexpectedly for passenger seat
Intermittent or permanent loss of passenger classification function

What to check

Read and record all stored/active DTCs and freeze-frame data with a diagnostic scanner
Check for related body/airbag codes and communications errors on CAN/LIN
Visually inspect seat area, sensor pad, connector boots, and wiring for damage, corrosion or moisture
Wiggle test wiring while observing live data to try to reproduce fault
Verify connectors are fully seated and locking tabs engaged
Check for evidence of aftermarket devices (heated seat mats, upholstery changes)

Signal parameters

Reference voltage: typically 5 V supply to sensor circuit (verify exact spec in service manual)
Signal type: analog voltage or resistance change; expected idle/sedentary signal usually within mid-range (~1–4 V) and changes when weight applied
Signal behavior: steady value with predictable step/change when occupant sits; should not be noisy or intermittent
Typical fault patterns: open circuit -> signal near 0 V or high impedance; short to battery -> near reference battery voltage; high resistance/poor ground -> attenuated or noisy signal
If sensor is on a data bus (LIN/CAN), the occupant classification message should be present and periodic

Diagnostic algorithm

Connect a capable scan tool, read and record B10B4 and any related codes and freeze-frame data. Attempt to reproduce while monitoring live sensor values.
Visually inspect connectors and wiring for damage, corrosion, water, or pin displacement; inspect under both front and rear of seat and along harness routing.
With vehicle and ignition in the specified test state, probe the sensor connector: verify reference voltage, sensor signal voltage, and ground continuity to chassis ground. Compare to manufacturer values.
Perform wiggle/seat-movement test while watching live data to identify intermittent wiring faults. Also check while applying light, medium, and heavy pressure on seat pad to see expected signal changes.
If wiring and power/ground are good but the signal is out of range or does not respond to load, disconnect the sensor and measure its resistance/voltage per service manual to confirm internal failure.
Inspect for contamination or foreign material in the cushion that could dampen or short the sensor; dry and clean if moisture is present and re-test.
If sensor and wiring test good, check occupant classification module and body control module communications and perform software/firmware update or module reset/calibration per manufacturer procedures.
Replace only the failed component (sensor pad or module) and any damaged wiring or connectors. After repairs, perform occupant classification calibration/initialization and confirm no additional codes and correct system behavior.

Likely causes

Intermittent open or short in sensor signal wire under seat
High resistance at connector or ground causing degraded signal amplitude
Failed sensor pad due to moisture or mechanical damage
Connector pins pushed out or wiring pinched by seat track movement

Fault status

⚠️ Status

Passenger seat occupancy sensor circuit — performance. The occupant classification system detected an unexpected or out‑of‑range sensor signal; passenger airbag enable/disable may be incorrect.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours