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Home / DTC / B2420 — Occupant Classification Sensor Circuit Fault — Front Passenger

B2420 — Occupant Classification Sensor Circuit Fault — Front Passenger

Detailed page for trouble code B2420.

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59brands
11,914generic
22,491specific
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Code

B2420

Generic B — Body

Occupant Classification Sensor Circuit Fault — Front Passenger

Brand: Generic
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the passenger seat sensor harness
  • Corroded, loose, damaged, or water-intruded connector under the passenger seat
  • Faulty occupant classification sensor (seat cushion mat / load sensor)
  • Faulty SRS/airbag control module or internal driver circuitry
  • Aftermarket seat covers, floor mats, or objects interfering with the sensor
  • Poor ground connection or shared-circuit damage (seat heater wiring, etc.)

Symptoms

  • SRS/airbag warning light illuminated on instrument cluster
  • Passenger airbag disabled message or indicator
  • Passenger presence/weight display incorrect or not available
  • Possible DTCs for related SRS/occupant classification circuits
  • Potential inability to arm passenger airbag depending on system logic

What to check

  • Retrieve DTCs and freeze-frame data with an SRS-capable scan tool; note related codes
  • Perform a visual inspection under the passenger seat for damaged wiring, connectors, or water stains
  • Check for aftermarket seat covers or heavy objects on the seat that could affect readings
  • Wiggle test harnesses and connectors while monitoring live data to see intermittent faults
  • Check connector pins for corrosion, bent pins, or poor mating
  • Verify battery voltage and proper vehicle ground integrity

Signal parameters

  • Reference supply typically provided by SRS module (common: ~5 VRef) — verify with service data
  • Sensor signal typically varies with occupant weight; expect a change from near 0 V (no load) to a higher voltage when loaded (exact values depend on manufacturer)
  • Open circuit: sensor line may read OL or very high resistance; short to ground: near 0 V; short to battery: near reference voltage
  • Resistance of seat mat/load-sensor elements commonly in the hundreds-to-thousands ohms range (consult OEM data for exact numbers)
  • Watch for inconsistent or noisy signal values in live data indicating intermittent wiring or a failing sensor

Diagnostic algorithm

  1. Read and record all SRS/OCS-related DTCs and freeze-frame data with an appropriate scan tool. Note any other SRS or communication codes.
  2. If safe and allowed by procedures, clear codes and see if B2420 returns to determine intermittence.
  3. Visually inspect the passenger seat area: connectors under the seat, harness routing, signs of contamination, seat heater wires, and aftermarket covers.
  4. Follow vehicle manufacturer SRS safety procedures: disable SRS power (battery disconnect and specified wait time) before disconnecting any airbag/seat connectors or performing repairs.
  5. With connectors exposed, inspect pins and terminals for corrosion, damage, or moisture. Repair or replace damaged connectors or harness sections.
  6. Reconnect, restore SRS power per procedure, and with a scan tool monitor live OCS data. Perform a wiggle test on harness and connectors to reproduce the fault.
  7. Measure reference voltage, signal voltage, and ground at the passenger seat sensor connector with ignition on (follow OEM safety guidance). Verify continuity back to the SRS module. Look for shorts to ground/power.
  8. If wiring and connectors check good, test the occupant classification sensor mat per OEM test procedure (resistance, output under known loads, or sensor self-test). Replace the sensor mat if out of specification.
  9. If sensor and wiring are OK but fault persists, check for related modules and CAN/SRS communications codes (e.g., U-codes) and consider SRS control module diagnostics or replacement only after confirming upstream components.
  10. After repair, clear codes, calibrate or reprogram OCS if required by the manufacturer, and perform functional verification (confirm passenger detection and no SRS faults).

Likely causes

  • Damaged connector or wiring under the passenger seat (common)
  • Failed occupant classification sensor mat (wear, moisture, or impact damage)
  • Short to ground or short to battery on the sensor signal or reference circuit
  • Corrosion from spilled liquids or humid environment
  • Fault in SRS control module (less common) or lost communications

Fault status

⚠️ Status
B2420 - Occupant Classification Sensor Circuit Fault (Front Passenger) — Check passenger seat sensor circuit, connector, and SRS module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours

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Code

B2420

HUMMER B — Body

Twilight Delay Pot Failure

Brand: HUMMER
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the passenger seat sensor harness
  • Corroded, loose, damaged, or water-intruded connector under the passenger seat
  • Faulty occupant classification sensor (seat cushion mat / load sensor)
  • Faulty SRS/airbag control module or internal driver circuitry
  • Aftermarket seat covers, floor mats, or objects interfering with the sensor
  • Poor ground connection or shared-circuit damage (seat heater wiring, etc.)

Symptoms

  • SRS/airbag warning light illuminated on instrument cluster
  • Passenger airbag disabled message or indicator
  • Passenger presence/weight display incorrect or not available
  • Possible DTCs for related SRS/occupant classification circuits
  • Potential inability to arm passenger airbag depending on system logic

What to check

  • Retrieve DTCs and freeze-frame data with an SRS-capable scan tool; note related codes
  • Perform a visual inspection under the passenger seat for damaged wiring, connectors, or water stains
  • Check for aftermarket seat covers or heavy objects on the seat that could affect readings
  • Wiggle test harnesses and connectors while monitoring live data to see intermittent faults
  • Check connector pins for corrosion, bent pins, or poor mating
  • Verify battery voltage and proper vehicle ground integrity

Signal parameters

  • Reference supply typically provided by SRS module (common: ~5 VRef) — verify with service data
  • Sensor signal typically varies with occupant weight; expect a change from near 0 V (no load) to a higher voltage when loaded (exact values depend on manufacturer)
  • Open circuit: sensor line may read OL or very high resistance; short to ground: near 0 V; short to battery: near reference voltage
  • Resistance of seat mat/load-sensor elements commonly in the hundreds-to-thousands ohms range (consult OEM data for exact numbers)
  • Watch for inconsistent or noisy signal values in live data indicating intermittent wiring or a failing sensor

Diagnostic algorithm

  1. Read and record all SRS/OCS-related DTCs and freeze-frame data with an appropriate scan tool. Note any other SRS or communication codes.
  2. If safe and allowed by procedures, clear codes and see if B2420 returns to determine intermittence.
  3. Visually inspect the passenger seat area: connectors under the seat, harness routing, signs of contamination, seat heater wires, and aftermarket covers.
  4. Follow vehicle manufacturer SRS safety procedures: disable SRS power (battery disconnect and specified wait time) before disconnecting any airbag/seat connectors or performing repairs.
  5. With connectors exposed, inspect pins and terminals for corrosion, damage, or moisture. Repair or replace damaged connectors or harness sections.
  6. Reconnect, restore SRS power per procedure, and with a scan tool monitor live OCS data. Perform a wiggle test on harness and connectors to reproduce the fault.
  7. Measure reference voltage, signal voltage, and ground at the passenger seat sensor connector with ignition on (follow OEM safety guidance). Verify continuity back to the SRS module. Look for shorts to ground/power.
  8. If wiring and connectors check good, test the occupant classification sensor mat per OEM test procedure (resistance, output under known loads, or sensor self-test). Replace the sensor mat if out of specification.
  9. If sensor and wiring are OK but fault persists, check for related modules and CAN/SRS communications codes (e.g., U-codes) and consider SRS control module diagnostics or replacement only after confirming upstream components.
  10. After repair, clear codes, calibrate or reprogram OCS if required by the manufacturer, and perform functional verification (confirm passenger detection and no SRS faults).

Likely causes

  • Damaged connector or wiring under the passenger seat (common)
  • Failed occupant classification sensor mat (wear, moisture, or impact damage)
  • Short to ground or short to battery on the sensor signal or reference circuit
  • Corrosion from spilled liquids or humid environment
  • Fault in SRS control module (less common) or lost communications

Fault status

⚠️ Status
B2420 - Occupant Classification Sensor Circuit Fault (Front Passenger) — Check passenger seat sensor circuit, connector, and SRS module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours

Similar codes

B2421 B2430 B1650 U0121 U0155
Repair manuals

Manual library for HUMMER

138

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Code

B2420

MITSUBISHI B — Body

Power integrated circuit

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring in the passenger seat sensor harness
  • Corroded, loose, damaged, or water-intruded connector under the passenger seat
  • Faulty occupant classification sensor (seat cushion mat / load sensor)
  • Faulty SRS/airbag control module or internal driver circuitry
  • Aftermarket seat covers, floor mats, or objects interfering with the sensor
  • Poor ground connection or shared-circuit damage (seat heater wiring, etc.)

Symptoms

  • SRS/airbag warning light illuminated on instrument cluster
  • Passenger airbag disabled message or indicator
  • Passenger presence/weight display incorrect or not available
  • Possible DTCs for related SRS/occupant classification circuits
  • Potential inability to arm passenger airbag depending on system logic

What to check

  • Retrieve DTCs and freeze-frame data with an SRS-capable scan tool; note related codes
  • Perform a visual inspection under the passenger seat for damaged wiring, connectors, or water stains
  • Check for aftermarket seat covers or heavy objects on the seat that could affect readings
  • Wiggle test harnesses and connectors while monitoring live data to see intermittent faults
  • Check connector pins for corrosion, bent pins, or poor mating
  • Verify battery voltage and proper vehicle ground integrity

Signal parameters

  • Reference supply typically provided by SRS module (common: ~5 VRef) — verify with service data
  • Sensor signal typically varies with occupant weight; expect a change from near 0 V (no load) to a higher voltage when loaded (exact values depend on manufacturer)
  • Open circuit: sensor line may read OL or very high resistance; short to ground: near 0 V; short to battery: near reference voltage
  • Resistance of seat mat/load-sensor elements commonly in the hundreds-to-thousands ohms range (consult OEM data for exact numbers)
  • Watch for inconsistent or noisy signal values in live data indicating intermittent wiring or a failing sensor

Diagnostic algorithm

  1. Read and record all SRS/OCS-related DTCs and freeze-frame data with an appropriate scan tool. Note any other SRS or communication codes.
  2. If safe and allowed by procedures, clear codes and see if B2420 returns to determine intermittence.
  3. Visually inspect the passenger seat area: connectors under the seat, harness routing, signs of contamination, seat heater wires, and aftermarket covers.
  4. Follow vehicle manufacturer SRS safety procedures: disable SRS power (battery disconnect and specified wait time) before disconnecting any airbag/seat connectors or performing repairs.
  5. With connectors exposed, inspect pins and terminals for corrosion, damage, or moisture. Repair or replace damaged connectors or harness sections.
  6. Reconnect, restore SRS power per procedure, and with a scan tool monitor live OCS data. Perform a wiggle test on harness and connectors to reproduce the fault.
  7. Measure reference voltage, signal voltage, and ground at the passenger seat sensor connector with ignition on (follow OEM safety guidance). Verify continuity back to the SRS module. Look for shorts to ground/power.
  8. If wiring and connectors check good, test the occupant classification sensor mat per OEM test procedure (resistance, output under known loads, or sensor self-test). Replace the sensor mat if out of specification.
  9. If sensor and wiring are OK but fault persists, check for related modules and CAN/SRS communications codes (e.g., U-codes) and consider SRS control module diagnostics or replacement only after confirming upstream components.
  10. After repair, clear codes, calibrate or reprogram OCS if required by the manufacturer, and perform functional verification (confirm passenger detection and no SRS faults).

Likely causes

  • Damaged connector or wiring under the passenger seat (common)
  • Failed occupant classification sensor mat (wear, moisture, or impact damage)
  • Short to ground or short to battery on the sensor signal or reference circuit
  • Corrosion from spilled liquids or humid environment
  • Fault in SRS control module (less common) or lost communications

Fault status

⚠️ Status
B2420 - Occupant Classification Sensor Circuit Fault (Front Passenger) — Check passenger seat sensor circuit, connector, and SRS module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours

Similar codes

B2421 B2430 B1650 U0121 U0155
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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+100 karma for a short comment :)
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