B0288

Code

Generic B — Body

Occupant classification sensor circuit malfunction

Brand: Generic

Type: B — Body

Views: UK: 11 EN: 18 RU: 8

AI status

Completed

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Page language: EN

Causes

Open, shorted or intermittent wiring between occupant classification sensor and SRS module
Corroded, loose or contaminated connector at the sensor or SRS module
Damaged occupant classification sensor (seat mat, pressure sensor array)
Poor or missing ground or reference voltage supply
Water intrusion or physical damage to the sensor/mat
Faulty SRS/airbag control module or software issue

Symptoms

SRS/airbag warning light illuminated on instrument panel
Passenger airbag disabled or enabled incorrectly (passenger airbag OFF message)
Seat belt reminders not behaving as expected for occupant presence
Inability to detect occupant weight or seat presence
Intermittent or permanent fault memory with B0288 stored

What to check

Read all SRS/airbag codes and freeze frame data with an OBD-II scan tool capable of SRS diagnostics
Check for additional related codes (other B-codes, U-codes) that may indicate module or CAN issues
Visually inspect seat area: connectors, wiring along seat rails, and sensor mat for damage or contamination
Verify connectors are fully seated and locking tangs engaged; inspect pins for corrosion or bent pins
Check battery voltage and perform key cycle to rule out low voltage events
Perform a wiggle test on harness while monitoring live data for intermittent change

Signal parameters

Reference (supply) voltage to sensor: typically a regulated 5 V reference — should be present and stable
Ground: continuity from sensor ground to chassis should be low (near 0 Ω) with good connection
Signal circuit: sensor output is a variable voltage/resistance dependent on occupancy — should change when seat is loaded/unloaded
Open-circuit: infinite resistance or no reference voltage indicates broken wiring or bad connector
Short to power: near battery voltage on signal where it should be low; short to ground: signal near 0 V — either indicates wiring fault
CAN/serial: if classification data is sent digitally, check that expected messages are present and within expected frequency using a capable scan tool

Diagnostic algorithm

Retrieve and record all SRS codes and freeze frame data. Note whether the fault is active or stored.
Check vehicle service information for manufacturer-specific occupant classification system wiring diagrams, component locations and expected signal values.
Visually inspect sensor mat, connector and harness under and around the passenger seat. Look for damage, contamination and moisture.
With battery connected, using a scan tool view live data for the occupant classification sensor output and passenger airbag status. Observe while sitting/un-sitting on the seat and while performing a wiggle test on the harness.
Verify reference voltage and ground at the sensor connector with a DMM. If reference voltage missing or out of range, trace back to SRS module/power source.
Measure signal circuit voltage/resistance at the sensor while changing load on the seat (empty vs. occupant). Confirm the signal changes logically and matches service manual ranges.
If signal is intermittent or wiring suspect, perform continuity and short-to-power/ground tests between the sensor connector and SRS module connector. Repair any open/shorted wiring.
If wiring and connectors check good but sensor output is out of expected range or non-responsive, replace or bench-test the occupant classification sensor/mat per manufacturer procedures.
If new sensor does not correct the fault, inspect SRS/airbag control module inputs and grounds; update or reprogram module software if manufacturer bulletin advises.
After repairs, clear codes and perform system self-test and road-simulated checks to confirm the fault does not return. Log final scan results.

Likely causes

Broken wire or pinched harness in seat-to-floor harness (common at seat rails)
Connector corrosion from spilled liquids or moisture under seat
Sensor element failure in the seat occupancy mat or load cell
Intermittent connection due to loose connector latch or bent pin
Defective SRS module input circuit or internal fault

Fault status

⚠️ Status

Occupant classification sensor circuit malfunction — possible open/short/intermittent signal, bad sensor or connector. SRS lamp may be lit and passenger airbag status may be incorrect.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours