B2728

Code

Generic B — Body

Passenger Seat Occupancy Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 9 EN: 7 RU: 7

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Page language: EN

Causes

Open or short in occupancy sensor wiring harness
Corroded, loose or damaged connector at the seat or module
Failed seat occupancy sensor (pressure pad, switch array, or capacitive mat)
Faulty seat control module or SRS module input circuit
Water intrusion, contamination, or physical damage to the seat sensor pad

Symptoms

SRS/airbag warning lamp illuminated
Passenger airbag may be disabled or incorrectly enabled
Seat belt reminder may not behave correctly for passenger seat
Diagnostic trouble code B2728 stored in airbag/occupant detection module
Possible inability to register a passenger on seat-occupancy display

What to check

Retrieve all stored DTCs and freeze-frame data with an OBD-II scan tool supporting body/SRS modules
Check for related codes in SRS or seat modules
Visually inspect passenger seat area for signs of water, damage, or foreign objects
Inspect seat-to-floor wiring harness and connectors for pin damage, corrosion, or chafing
Perform a wiggle test of wiring while observing data stream or lamp to reproduce intermittent fault
Confirm SRS disable/repair procedures for the vehicle before attempting connector removal or seat repair

Signal parameters

Reference/supply: typically a module reference (commonly 5 V) or switched supply — verify with vehicle wiring diagram
Signal: occupancy circuit usually presents a variable voltage or resistance that changes when weight is applied (expect a significant change between empty vs occupied states)
Ground: circuit should have good continuity to chassis ground
Fault indications: open circuit (no signal), short to ground (≈0 V), or short to supply (≈reference voltage)

Diagnostic algorithm

Read and record DTCs and live data from the SRS/occupant detection module.
Review manufacturer wiring diagram for passenger seat occupancy sensor circuit (identify connectors, pinouts, reference voltage, and signal path).
With ignition ON (follow SRS safety procedures), backprobe the occupancy sensor connector: verify reference voltage, ground continuity, and signal behavior while seat is empty and then gently apply weight to the seat. Compare to expected changes.
If signal is missing/erratic, inspect and test harness from seat connector to module for continuity, shorts to ground, and shorts to battery. Repair any wiring damage.
Inspect connector terminals for corrosion, bent pins, or loose terminals; repair or replace connector as required.
If wiring and connectors are good, test or replace the seat occupancy sensor pad per manufacturer procedure. Many sensors are integral to the seat cushion and require seat removal.
If sensor replacement does not clear the fault, test/replace the seat control or SRS module input circuit as directed by manufacturer diagnostics.
After repairs, clear codes and perform full system scan and a functional test (confirm sensor reports occupied/unoccupied correctly and SRS lamp is off).
Follow all SRS safety procedures: disable SRS power source and localize stored energy before seat removal. Use OEM repair information for deployment-related components.

Likely causes

Poor connector contact at the passenger seat plug
Broken or pinched wire in the harness under the seat (movement/wear)
Damaged sensor pad from moisture or impact
Intermittent fault due to connector corrosion or displaced terminal

Fault status

⚠️ Status

Passenger seat occupancy sensor circuit malfunction — signal out of range, open, or short detected. May affect passenger airbag enabling and seatbelt/occupant detection functions.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours