Code
B2854
Generic
B — Body
Occupant Classification Sensor Circuit Fault
AI status
Completed
Completed
100%
Causes
- Damaged or disconnected sensor mat or sensor module
- Open, shorted, corroded, or chafed wiring/connectors between sensor and SRS module
- Poor power supply or ground to the occupant classification module
- Water intrusion or contamination of seat cushion/sensors
- Seat cover or aftermarket accessory interfering with sensor operation
- Faulty occupant classification module or related control unit software error
Symptoms
- SRS/airbag warning lamp illuminated
- Passenger airbag ON/OFF indicator incorrect or stuck
- Passenger airbag disabled when seat is occupied (or enabled when empty)
- Seat belt reminder or chime behavior abnormal
- Diagnostic trouble codes stored for occupant classification or SRS
What to check
- Read and record all stored SRS and occupant classification codes and freeze-frame data with a capable scan tool.
- Check for technical service bulletins or recalls related to occupant classification for the vehicle.
- Visually inspect seat, connectors, and wiring under seat for damage, corrosion, or signs of water intrusion.
- Verify proper power (usually 5 V reference or 12 V supply depending on system) and ground at the occupant classification module connector per vehicle spec.
- Perform wiggle test on harness and connectors while monitoring live sensor values or DTCs with scan tool.
- Remove seat cover (if serviceable) and inspect sensor mat for contamination or physical damage.
Signal parameters
- Reference voltage: typically ~5 V (varies by manufacturer) to sensor module
- Signal voltage: may vary between ~0.2–4.8 V depending on occupied state (check OEM spec)
- Ground: close to 0 V under normal conditions (< 0.5 V at module ground pin)
- Resistance of mat sensors (if applicable): variable; many are kΩ-range when intact—compare to vehicle spec
- Live data: occupancy state and raw sensor values should change when weight placed/removed on seat
Diagnostic algorithm
- Observe safety precautions: follow manufacturer SRS procedures (disable battery or follow specified wait time) before disconnecting airbag connectors or performing seat work.
- Use a scan tool to read all SRS/occupant classification codes and view live data while performing tests.
- Visually inspect seat area, connectors, and wiring under the seat for physical damage, corrosion, or water; repair any obvious issues.
- With ignition on, verify reference voltage and supply voltage at the occupant classification module connector (compare to vehicle-specific values).
- Check module ground integrity (measure resistance to chassis ground).
- Monitor live sensor data while placing known weight on the seat and removing it; observe for expected changes and stability. Perform wiggle test to reproduce the fault.
- If the signal is open/shorted, isolate section of harness: perform continuity and resistance checks between module connector and sensor mat connectors; repair broken wires or shorts.
- If wiring and connectors are good but sensor values are out of range or do not change, disconnect sensor mat and measure mat resistance per service data; if out of spec, replace sensor mat.
- If module power, ground, wiring, and sensor mat are within spec, suspect occupant classification module failure—verify with known-good module if available.
- After repair or replacement, perform required occupant classification system calibration/initialization per manufacturer procedure, clear codes, and verify repair by monitoring live data and confirming lamp/instrument cluster behavior.
Likely causes
- Loose or corroded connector at occupant classification sensor/module
- Damaged wiring harness under seat (pinched, cut, or short to chassis)
- Faulty occupant classification sensor mat (wear, water damage)
- Module failure or internal sensor electronics fault
Fault status
Status
The vehicle's occupant classification sensor circuit is reporting an electrical fault (open, short, out-of-range, or communication problem). The SRS control unit may disable or misreport passenger airbag status until the fault is corrected and the system recalibrated.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
Similar codes
Repair manuals
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Code
B2854
HYUNDAI
B — Body
HSDPA USB Communication Error
AI status
Completed
Completed
100%
Causes
- Damaged or disconnected sensor mat or sensor module
- Open, shorted, corroded, or chafed wiring/connectors between sensor and SRS module
- Poor power supply or ground to the occupant classification module
- Water intrusion or contamination of seat cushion/sensors
- Seat cover or aftermarket accessory interfering with sensor operation
- Faulty occupant classification module or related control unit software error
Symptoms
- SRS/airbag warning lamp illuminated
- Passenger airbag ON/OFF indicator incorrect or stuck
- Passenger airbag disabled when seat is occupied (or enabled when empty)
- Seat belt reminder or chime behavior abnormal
- Diagnostic trouble codes stored for occupant classification or SRS
What to check
- Read and record all stored SRS and occupant classification codes and freeze-frame data with a capable scan tool.
- Check for technical service bulletins or recalls related to occupant classification for the vehicle.
- Visually inspect seat, connectors, and wiring under seat for damage, corrosion, or signs of water intrusion.
- Verify proper power (usually 5 V reference or 12 V supply depending on system) and ground at the occupant classification module connector per vehicle spec.
- Perform wiggle test on harness and connectors while monitoring live sensor values or DTCs with scan tool.
- Remove seat cover (if serviceable) and inspect sensor mat for contamination or physical damage.
Signal parameters
- Reference voltage: typically ~5 V (varies by manufacturer) to sensor module
- Signal voltage: may vary between ~0.2–4.8 V depending on occupied state (check OEM spec)
- Ground: close to 0 V under normal conditions (< 0.5 V at module ground pin)
- Resistance of mat sensors (if applicable): variable; many are kΩ-range when intact—compare to vehicle spec
- Live data: occupancy state and raw sensor values should change when weight placed/removed on seat
Diagnostic algorithm
- Observe safety precautions: follow manufacturer SRS procedures (disable battery or follow specified wait time) before disconnecting airbag connectors or performing seat work.
- Use a scan tool to read all SRS/occupant classification codes and view live data while performing tests.
- Visually inspect seat area, connectors, and wiring under the seat for physical damage, corrosion, or water; repair any obvious issues.
- With ignition on, verify reference voltage and supply voltage at the occupant classification module connector (compare to vehicle-specific values).
- Check module ground integrity (measure resistance to chassis ground).
- Monitor live sensor data while placing known weight on the seat and removing it; observe for expected changes and stability. Perform wiggle test to reproduce the fault.
- If the signal is open/shorted, isolate section of harness: perform continuity and resistance checks between module connector and sensor mat connectors; repair broken wires or shorts.
- If wiring and connectors are good but sensor values are out of range or do not change, disconnect sensor mat and measure mat resistance per service data; if out of spec, replace sensor mat.
- If module power, ground, wiring, and sensor mat are within spec, suspect occupant classification module failure—verify with known-good module if available.
- After repair or replacement, perform required occupant classification system calibration/initialization per manufacturer procedure, clear codes, and verify repair by monitoring live data and confirming lamp/instrument cluster behavior.
Likely causes
- Loose or corroded connector at occupant classification sensor/module
- Damaged wiring harness under seat (pinched, cut, or short to chassis)
- Faulty occupant classification sensor mat (wear, water damage)
- Module failure or internal sensor electronics fault
Fault status
Status
The vehicle's occupant classification sensor circuit is reporting an electrical fault (open, short, out-of-range, or communication problem). The SRS control unit may disable or misreport passenger airbag status until the fault is corrected and the system recalibrated.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
Similar codes
Repair manuals
Manual library for HYUNDAI
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Code
B2854
MITSUBISHI
B — Body
Side latch hall sensor:no signal
AI status
Completed
Completed
100%
Causes
- Damaged or disconnected sensor mat or sensor module
- Open, shorted, corroded, or chafed wiring/connectors between sensor and SRS module
- Poor power supply or ground to the occupant classification module
- Water intrusion or contamination of seat cushion/sensors
- Seat cover or aftermarket accessory interfering with sensor operation
- Faulty occupant classification module or related control unit software error
Symptoms
- SRS/airbag warning lamp illuminated
- Passenger airbag ON/OFF indicator incorrect or stuck
- Passenger airbag disabled when seat is occupied (or enabled when empty)
- Seat belt reminder or chime behavior abnormal
- Diagnostic trouble codes stored for occupant classification or SRS
What to check
- Read and record all stored SRS and occupant classification codes and freeze-frame data with a capable scan tool.
- Check for technical service bulletins or recalls related to occupant classification for the vehicle.
- Visually inspect seat, connectors, and wiring under seat for damage, corrosion, or signs of water intrusion.
- Verify proper power (usually 5 V reference or 12 V supply depending on system) and ground at the occupant classification module connector per vehicle spec.
- Perform wiggle test on harness and connectors while monitoring live sensor values or DTCs with scan tool.
- Remove seat cover (if serviceable) and inspect sensor mat for contamination or physical damage.
Signal parameters
- Reference voltage: typically ~5 V (varies by manufacturer) to sensor module
- Signal voltage: may vary between ~0.2–4.8 V depending on occupied state (check OEM spec)
- Ground: close to 0 V under normal conditions (< 0.5 V at module ground pin)
- Resistance of mat sensors (if applicable): variable; many are kΩ-range when intact—compare to vehicle spec
- Live data: occupancy state and raw sensor values should change when weight placed/removed on seat
Diagnostic algorithm
- Observe safety precautions: follow manufacturer SRS procedures (disable battery or follow specified wait time) before disconnecting airbag connectors or performing seat work.
- Use a scan tool to read all SRS/occupant classification codes and view live data while performing tests.
- Visually inspect seat area, connectors, and wiring under the seat for physical damage, corrosion, or water; repair any obvious issues.
- With ignition on, verify reference voltage and supply voltage at the occupant classification module connector (compare to vehicle-specific values).
- Check module ground integrity (measure resistance to chassis ground).
- Monitor live sensor data while placing known weight on the seat and removing it; observe for expected changes and stability. Perform wiggle test to reproduce the fault.
- If the signal is open/shorted, isolate section of harness: perform continuity and resistance checks between module connector and sensor mat connectors; repair broken wires or shorts.
- If wiring and connectors are good but sensor values are out of range or do not change, disconnect sensor mat and measure mat resistance per service data; if out of spec, replace sensor mat.
- If module power, ground, wiring, and sensor mat are within spec, suspect occupant classification module failure—verify with known-good module if available.
- After repair or replacement, perform required occupant classification system calibration/initialization per manufacturer procedure, clear codes, and verify repair by monitoring live data and confirming lamp/instrument cluster behavior.
Likely causes
- Loose or corroded connector at occupant classification sensor/module
- Damaged wiring harness under seat (pinched, cut, or short to chassis)
- Faulty occupant classification sensor mat (wear, water damage)
- Module failure or internal sensor electronics fault
Fault status
Status
The vehicle's occupant classification sensor circuit is reporting an electrical fault (open, short, out-of-range, or communication problem). The SRS control unit may disable or misreport passenger airbag status until the fault is corrected and the system recalibrated.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
Similar codes
Repair manuals
Manual library for MITSUBISHI
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