Code
B29E2
Generic
B — Body
Passenger Presence Detection Sensor Circuit Short to Ground
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UK: 1
EN: 1
RU: 1
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring causing the sensor signal conductor to contact chassis ground
- Corroded or pushed-back connector pins creating a low-resistance path to ground
- Faulty passenger presence sensor (seat pad / sensor mat) with internal short
- Water intrusion or contamination in the seat or connector causing leakage to ground
- Aftermarket seat/heater installations or repairs that disturbed wiring
- Faulty occupant classification / restraint control module (less common)
Symptoms
- Passenger airbag status light on or airbag disabled for passenger side
- DTC B29E2 stored in occupant classification / body control module
- Passenger detection may always read ‘no occupant’ or produce inconsistent readings
- Possible supplemental restraint system (SRS) warning or reduced system functionality
- Intermittent faults when seat is moved or after sitting on seat if wiring is disturbed
What to check
- Read all related DTCs and freeze frame data from occupant classification / SRS module
- Visually inspect seat area, connectors, and wiring harness routing for damage or water
- Check connectors for corrosion, pushed out pins, or bent terminals
- Backprobe the sensor signal connector and measure voltage with key-on (per manufacturer safety procedure)
- Measure resistance between the sensor signal pin and chassis ground with power off
- Inspect for aftermarket devices (seat heaters, alarms) that may share or contact the harness
Signal parameters
- Reference supply (Vref) to occupant sensor electronics typically ~5.0 V (±0.5 V) — verify with vehicle documentation
- Normal signal voltage range (varies by system) typically within ≈0.5–4.5 V when not shorted; exact expected idle depends on manufacturer
- Short-to-ground condition: signal line measured near 0–0.5 V with system powered
- With battery disconnected, resistance from signal wire to chassis ground should be very high (kΩs). A short will show very low resistance (
- Note: exact voltages/resistances vary by vehicle — consult service manual for precise values
Diagnostic algorithm
- Read and record all stored codes and freeze frame; note any related SRS/communication codes.
- Follow safety procedures for SRS/occupant system work (battery disconnect or manufacturer-specific restraint system disable if required).
- Perform a careful visual inspection of the passenger seat, underside, and carpet area for damaged wires, pinched sections, or evidence of liquid intrusion.
- Inspect and unplug the passenger presence sensor connector(s); check pins for corrosion, bent/pushed-back pins, or contamination. Reconnect firmly and re-test.
- With key on (or safe power state per service manual) backprobe the sensor signal wire at the connector and measure voltage. A reading near 0 V indicates a short to ground.
- With battery disconnected/power off, measure resistance between the signal wire and chassis ground. Low resistance indicates a direct short — trace wiring toward the seat and under-dash areas.
- Isolate the short by disconnecting sections: unplug the seatback/cushion sensor connector(s) and measure the line at each harness splice/connector to find the location where resistance jumps to high (open/no-short).
- If the short is localized to the sensor or seat cushion, remove the seat and inspect/replace the sensor mat or harness pigtail as required.
- If wiring to the body is damaged, repair or replace the harness section using correct gauge, routing, and protective sleeving; avoid solder joints in areas subject to flex; use manufacturer-approved repair methods.
- If wiring and sensor check good, consider replacing or reprogramming the occupant classification/control module only after confirming harness and sensor integrity.
- After repair, clear codes, perform system relearn or calibration procedures required by the manufacturer, and test system function with appropriate occupant weights/positions and final scan tool verification.
Likely causes
- Pinched harness where it passes through seat frame or under carpet, shorting to chassis
- Connector backshell contacting seat frame producing a ground short under load
- Seat cushion sensor mat damaged (puncture, sewn-through or worn) creating internal short
- Connector terminal corrosion from spilled liquids causing conductive path to ground
- Recent seat removal/installation with harness routed incorrectly and grounded
Fault status
Status
Passenger Presence Detection sensor circuit indicates a short to ground. Occupant classification may be invalid or passenger airbag disabled. Inspect sensor wiring, connectors, and seat sensor for shorts or contamination.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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