B0234

Code

Generic B — Body

Occupant Classification System (OCS) Sensor Fault

Brand: Generic

Type: B — Body

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AI status

Completed

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Page language: EN

Causes

Damaged or corroded connector or wiring harness to the OCS sensor
Faulty OCS load/pressure/seat mat sensor module
Poor ground or supply voltage problems to the sensor
Intermittent connection (broken wire, loose pin) or short to power/ground
Contamination, water intrusion or deformation of seat cushion/mat affecting sensor readings
Software calibration fault or corrupted sensor/module software

Symptoms

SRS / airbag warning lamp illuminated
Possible disablement of passenger airbag or incorrect airbag-on/off indicator
Vehicle diagnostic trouble code B0234 stored in airbag/OCS module
Inconsistent or no occupancy detection for passenger seat
Intermittent or permanent inability to correctly classify occupant weight

What to check

Read and record freeze frame and all related SRS/OCS codes with a qualified scan tool
Visually inspect seat connectors, harness routing, and seat mounting for damage or pin push-out
Check for water, debris, or damage to the seat cushion/mat area where OCS sensors are located
Verify vehicle battery voltage and main power/ground circuits to airbag/OCS modules
Check for Technical Service Bulletins (TSBs) or calibration procedures for OCS on this model

Signal parameters

Sensor supply voltage (typically 5 V reference) — present and stable
Sensor ground continuity — low resistance to chassis ground
Seat mat/load sensor resistance or capacitance value — compared to factory specification
Raw occupancy/weight values or sensor channel voltages reported by scan tool
CAN/LIN diagnostic messages from OCS module — presence and expected periodic updates
Open/short indications on individual sensor channels (in ohms or volts as per factory data)

Diagnostic algorithm

Safety first: follow manufacturer procedure to disable SRS system (battery disconnect and wait time) before working on seat/airbag wiring.
Use a diagnostic scan tool to confirm B0234 and read related OCS/SRS codes and live data channels; note when the code sets (key-on, during driving, after seat movement).
Visually inspect the passenger seat area thoroughly: connectors under the seat, seat track chaffing points, and seat cushion for contamination or damage.
With SRS safe state maintained per manufacturer, inspect and reseat the OCS connector(s). Check pins for corrosion, bent pins, or pushed-out terminals.
Perform continuity and resistance checks on the sensor harness from the OCS connector to the control module. Wiggle harness while monitoring live data to catch intermittent faults.
Measure sensor supply and ground at the connector with key on; verify reference voltage (typ. 5 V) and good ground. Compare sensor channel voltages/resistances to spec.
If available, use the scan tool to monitor raw sensor/weight values while applying known loads (e.g., manufacturer-approved test weights or a calibrated test jig) to the seat to confirm response.
If harness and connectors test good but sensor values are out of spec, replace the suspect seat mat/sensor. Re-install and perform OCS calibration per factory procedure.
If replacement sensor does not fix the issue, test/replace the occupant classification control module or related SRS module following manufacturer diagnostic flow.
After any repair, clear codes, perform required OCS calibrations, and re-check live data and self-tests. Confirm no recurrence of B0234 and that airbag indicators behave correctly.

Likely causes

Connector corrosion or pin damage at the seat/OCS sensor
Broken or shorted wiring in the seat harness (common after seat removal or repair)
Defective seat mat/load sensor element
Poor ground or intermittent supply voltage to the sensor
Sensor needs recalibration after seat/airbag or interior service

Fault status

⚠️ Status

Stored DTC B0234 — Occupant Classification System (OCS) Sensor Fault. May cause passenger airbag disablement or SRS warning lamp; further inspection and calibration required.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours