B3028

Code

Generic B — Body

Passenger Presence Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 16 EN: 26 RU: 21

AI status

Completed

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Page language: EN

Causes

Faulty passenger presence (occupant classification) sensor module or mat
Damaged, corroded or disconnected wiring or connector in sensor circuit
Short to battery voltage or short to ground on the sensor signal wire
Water/moisture intrusion or contamination of the sensor or connector
Improperly installed or incompatible aftermarket seat cover or padding
Faulty SRS / occupant classification control unit (ECU) or software issue

Symptoms

SRS / airbag warning light illuminated
Passenger airbag status indicator may show airbag disabled (or unexpected state)
Seat belt reminder or occupant indicator behaves incorrectly
Inability to detect child seat or wrong occupant classification
DTC B3028 stored (may be current or intermittent); drivability typically unaffected

What to check

Connect a capable scan tool; read DTC(s) and freeze frame/fault status and note if code is current or historic
Visually inspect passenger seat, underside, wiring harness, and connectors for damage, corrosion, or moisture
Check for aftermarket seat covers, cushions, or objects that may affect the sensor
Monitor live data/occupant detection signal while applying/removing weight from the seat
Perform wiggle test of wiring and connector while observing live data for intermittent faults
Disconnect sensor and observe if code persists to help isolate sensor vs wiring/ECU

Signal parameters

Reference voltage typically present at sensor connector (often 5 V supply) — verify stable reference
Sensor output voltage should change as load/weight on the seat changes (0–5 V range depending on design)
Open circuit (infinite resistance) or a short to ground/voltage on the signal line indicates a fault
No communication or out-of-range values on occupant classification bus (if networked) indicate sensor/module fault
Live-data flags: occupancy detected / not detected / invalid — should change with applied weight

Diagnostic algorithm

Use a scan tool to confirm B3028 and check for related SRS/occupant classification codes.
Inspect the passenger seat area, connector, and wiring for visible damage, corrosion, or moisture. Remove seat covers if needed.
Check for aftermarket seat covers or objects between the mat and occupant; remove and retest.
With ignition on, monitor occupant sensor live data while applying known weight to the seat. Note whether the sensor output changes.
Perform a wiggle test: move the seat and harness while observing live data for intermittent faults. Recreate conditions if code is intermittent.
Measure reference voltage, signal voltage, and ground at the sensor connector per service manual. Look for open, short to ground, or short to battery.
If wiring and connector check good, measure sensor resistance/characteristics against service specifications or substitute a known-good sensor if available.
Repair any damaged wiring, clean/replace corroded connectors, or replace the passenger presence sensor/module as required.
After repairs, clear codes, perform required occupant sensor recalibration/initialization per manufacturer procedure, then verify with live data and road test.
If fault persists after sensor and wiring verification, consider SRS/occupant classification ECU fault and follow advanced diagnostics or consult manufacturer technical service information.

Likely causes

Corroded/disconnected connector at the passenger presence sensor
Damaged wiring harness (pinched at seat rails or under-seat area)
Failed/passive sensor element (pressure mat or load cell) in the seat
Contamination (water, debris) causing sensor short or leakage
Seat cover or cushion altering sensor readings

Fault status

⚠️ Status

Passenger Presence Sensor Circuit Malfunction — occupant classification/airbag enablement may be impaired. SRS warning or passenger airbag disabled indicator may be illuminated.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours