B1149: Airbag Module Voltage Fault

Hardware fault

What B1149 means

Restraint modules need stable voltage to charge their firing reserves and run their internal checks. The control unit monitors its own supply and compares it against upper and lower limits. When the voltage strays past either one, whether too low to work with or high enough to cause damage, the module stores B1149 and disables deployment.

That means the fault often lives outside the airbag system entirely. A tired battery, a corroded ground, a failing alternator, or a loose connection in the supply circuit can all produce it. The module is reporting honestly about what it is being fed rather than complaining about itself.

Common causes

• A weak or failing battery that drops voltage under load
• A charging system producing voltage that is too high or unstable
• Corroded or loose battery terminals and cable ends
• A poor ground connection at the control unit or on the body
• A damaged or high resistance supply wire feeding the module
• Voltage disturbance from a jump start or an improperly installed accessory

Crash data or hardware fault?

B1149 is a live condition the module is measuring, not a crash record. It clears once the supply is stable and within range through a full key cycle. Crash data is what gets written when airbags fire, and it stays locked in module memory until a reset removes it, which no amount of electrical repair will do.

Does our reset clear it?

Sending the module in does not repair a charging system. Our reset service is for stored deployment data, so it is relevant here only if the vehicle also deployed. Fix the voltage problem first, since a module running on bad power can set several unrelated restraint codes and send you chasing parts that are perfectly fine.

Which makes throw it

B1149 is the Subaru airbag ECU power supply voltage fault, which is one of the five character B codes in its SRS list alongside the shorter numeric codes. It is worth checking first when several restraint codes appear at once.

What to do next

Load test the battery and check charging voltage before anything else, because bad power explains this code most of the time. Clean and tighten the battery terminals and the body grounds. Measure voltage right at the control unit connector while the engine runs, since a reading that is fine at the battery can drop across a corroded wire. Once power is steady, clear the code and see what remains, then call 501-988-0611 if module questions are left. Related codes: B1000, B11E0, B1620.