B29E2

Code

Generic B — Body

Passenger Presence Detection Sensor Circuit Short to Ground

Brand: Generic

Type: B — Body

Views: UK: 11 EN: 22 RU: 14

AI status

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Page language: EN

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