29: Occupant Detection System Failure

Hardware fault

What 29 means

Occupant detection weighs or senses what is in the passenger seat and reports it so the system can enable or suppress the passenger airbag. Subaru splits that job between sensing hardware in the seat cushion and a control module that interprets it. Code 29 says one of those two has failed rather than pointing at a specific wire.

Because the definition covers both the sensor and the module, the first task is deciding which one is at fault. That usually means checking whether the module is receiving sensible sensor data at all. Seats take abuse, get removed, and collect spilled drinks, so the sensing side in the cushion carries more risk than the module.

Common causes

• A failed sensing mat or sensor assembly inside the passenger seat cushion
• A failed occupant detection control module
• Liquid spilled into the seat reaching the sensing hardware
• Damage from heavy loads placed on the passenger seat or from seat removal
• Aftermarket seat covers or heaters installed over the sensing components
• A connector under the seat that is corroded or was disturbed during work

Crash data or hardware fault?

Code 29 reports a live hardware fault about a component rather than a deployment record. The system rechecks occupant detection on every key cycle and the code returns after any scan tool clear until the part is repaired. Crash data is the permanent entry made when airbags fire, and a module reset is what clears that.

Does our reset clear it?

Our mail-in reset addresses stored crash data in restraint modules. It does not repair a failed seat sensor or a failed occupant detection module. Fix the sensing hardware, then run the calibration the system requires so the module trusts its new readings. If the car also deployed and crash data is stored, send the restraint module in after the seat work is done.

Which makes throw it

Subaru assigns code 29 to occupant detection system failure. It sits in a small group with 2A and 2B, which cover calibration and wrong parts on the same system, so read all the stored codes together before deciding what to replace.

What to do next

Scan for the companion codes first, because 2A and 2B change the diagnosis completely and often appear with this one. Check the under seat connector for corrosion and a proper latch. Look for evidence of spills, seat covers, or aftermarket heaters in the cushion. Once you know whether the sensor or the module failed, we can source genuine OEM Subaru occupant detection parts, and you can reach us at 501-988-0611. Related codes: 26, 2A, 33.