B1661 reports a failure in the passenger airbag on and off indicator circuit. That indicator shows occupants whether the passenger airbag is currently enabled, and the control unit has found its circuit reading wrong.
The on and off indicator is driven by the restraint system so occupants can see the state of the passenger airbag at a glance. The control unit watches the circuit feeding that indicator and expects a specific load. An open bulb, a broken wire, or a short changes what it measures, and B1661 is the result.
Nothing about this code says the passenger airbag is damaged. The firing loop and the indicator circuit are separate, and a car can have a perfectly healthy airbag with a dead indicator. What it does mean is that occupants lose the display telling them whether the airbag is on or off.
B1661 is a live circuit fault the module measures on every key cycle, so it clears as soon as the indicator circuit reads correctly. Crash data is the separate category, written only when restraints deploy, locked into the module, and removed through a reset rather than any repair at the car.
Clearing the module changes nothing about a bad indicator circuit. The control unit rechecks it at the next key on and stores the code again. Repair the bulb, the wire, or the connector, then watch the indicator through its startup check to confirm it works. Mail-in reset applies only when stored crash data is also present in the module.
On Subaru, B1661 covers the passenger airbag on and off indicator. Its definition overlaps with numeric code 26 in the same system, so read the exact code from the scan tool before deciding which indicator circuit you are chasing.
Watch the indicator during the lamp check at key on, because one that never illuminates points at the bulb or its feed straight away. Get behind the indicator and check the connector for a loose fit or corrosion. Test continuity back to the control unit before suspecting the module itself. If the circuit tests good and the module is not driving the indicator, call 501-988-0611 and we will go over control unit options with you. Related codes: B1656, B1800, B1038.
Trace the wiring and connectors first. If the module still holds the fault after the repair, mail it to us and we will clear it.
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Do not see it listed? Request a part or call 501-988-0611.