B2822

Code

Generic B — Body

Passenger Occupant Detection Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 11 EN: 13 RU: 17

AI status

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Page language: EN

Causes

Loose, corroded or disconnected connector at the seat sensor or module
Damaged wiring harness (pinched, chafed, broken, or shorted) under the seat
Faulty passenger occupant detection sensor (pressure/weight or mat sensor)
Poor ground or low reference voltage to the sensor circuit
Faulty occupant classification module or airbag control module input
Water/moisture intrusion or contamination of the sensor mat

Symptoms

Passenger airbag indicator (warning lamp) illuminated or flashing
Passenger airbag disabled unexpectedly or does not enable when seat occupied
Seatbelt/occupant reminders incorrect for passenger seat
Diagnostic trouble codes stored for passenger occupant detection circuit
Possible inability to run occupant classification system calibration

What to check

Retrieve and record all stored codes and freeze frame data with a capable scan tool; clear codes and attempt to re-run test to reproduce.
Visually inspect the passenger seat, underside, and wiring harness for damage, pinching, disconnected or corroded connectors and signs of water ingress.
Ensure seat mounting and connectors are properly seated after any recent service or seat removal.
Check for proper power and ground at the sensor connector (use wiring diagram/service data).
Wiggle wiring harness and connectors while monitoring live data or the fault status to detect intermittent faults.
Measure sensor signal voltage or resistance per vehicle service data with seat empty and with known/load to confirm change in expected signal.

Signal parameters

Reference supply: typically a regulated reference (often 5 V) — verify exact value from service data.
Signal line: expected to be within 0–5 V depending on system; an empty seat and occupied state should show distinct, consistent voltage levels per OEM specs.
Ground: continuity to chassis ground should be very low (near 0 Ω); high resistance indicates poor ground.
Open-circuit or short to battery/ground will produce out-of-range voltage (0 V or battery voltage) — compare to service data.
Resistance or capacitance values for pressure mats are manufacturer-specific — measure and compare to service manual values before replacing.

Diagnostic algorithm

Connect scan tool, read and record codes and freeze frame. Note whether code is current or historic and any combination with other airbag/communication codes.
Clear codes, then attempt to re-create the fault to confirm it returns (try sitting in passenger seat or perform system self-test).
Perform visual inspection of seat, connectors, sensor mat, and wiring harness for obvious damage, water, or disconnected plugs.
Identify sensor connector and consult wiring diagram. Probe for reference voltage, signal voltage and ground at the connector with key on. Compare to service specifications.
With seat empty and then with a test load (an approved weight per OEM procedure or a technician sitting), observe signal change on live data; no change indicates sensor or wiring issue.
Perform wiggle/stress test on harness and connectors while monitoring live data or scanning for fault set — helps find intermittent faults.
Check continuity and resistance of sensor circuit pins back to the control module; repair any opens, shorts or high-resistance grounds.
If connectors and wiring test good, swap with a known-good sensor (if available) or replace sensor mat per procedures. Some systems require module re-learn or calibration after replacement.
If wiring and sensor are good, test/inspect occupant classification module and airbag control module connections; check for related communication codes.
After repair, clear codes and perform required calibration or occupant classification relearn. Verify system behavior and that the passenger airbag status is correct under several occupant conditions.

Likely causes

Disconnected or loose seat harness connector
Broken/chafed wiring at seat harness where it moves
Failed sensor mat caused by moisture or mechanical damage
Poor ground at seat or reference voltage missing
Module fault or bad connector pins at the control unit

Fault status

⚠️ Status

Passenger Occupant Detection Sensor Circuit Malfunction — electrical fault detected in passenger occupancy sensor circuit. May disable passenger airbag or illuminate warning lamp until repaired and cleared.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.0 hours

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