01578: Passenger Airbag Off Lamp

Circuit fault

What 01578 means

K145 is the small telltale that shows the front passenger whether their airbag is armed or switched off. On cars fitted with a key-operated cutoff or an occupant detection system, the restraint control module drives that lamp and monitors the circuit while it does. A burned filament, a broken feed wire, or a poor ground puts the measurement outside the accepted window, and the module stores 01578.

None of this describes the airbag itself. It describes the indicator that reports the airbag state, which is why the main airbag warning light on the cluster usually comes on at the same time. The module counts the telltale as part of the restraint system, so it flags a lamp circuit it cannot verify even when every inflator loop reads perfectly normal.

Common causes

• A burned out bulb or dead LED in the passenger airbag off indicator
• A loose or corroded connector behind the console trim or dash panel where the indicator mounts
• Broken wiring in the lamp branch, common after stereo, console, or dash disassembly
• A poor ground at the indicator circuit ground point
• A failed passenger airbag cutoff key switch sending the module a state it cannot confirm
• An output driver inside the restraint module that no longer switches the lamp

Crash data or hardware fault?

This is a live circuit fault, not stored crash data. The module rechecks the K145 branch every time the ignition comes on, so the entry follows the actual condition of the circuit and drops out once the reading is normal again. Crash data works the other direction. It is written the moment airbags deploy and stays locked in module memory where no scan tool can reach it.

Does our reset clear it?

Resetting the module does not repair a lamp circuit. The self test runs again within seconds of the next key cycle and writes 01578 straight back. Fix the bulb, connector, ground, or wiring first. Our mail-in reset service is for modules holding deployment data from a crash, and if this module is also holding that kind of record, we can clear it once the physical repairs are finished.

Which makes throw it

01578 shows up on Audi. It is part of the Volkswagen Audi Group five-digit fault code set, so the number and the K145 component label read the same across Audi models that carry a passenger airbag off indicator.

What to do next

Pull the indicator and check the bulb or LED first, because a dead lamp is the cheapest and most common answer. If the lamp is good, back-probe the connector for power and ground with the key on and see which side is missing. A circuit that reads correct at the lamp but still sets the code points back at the restraint module output, and at that point give us a call at 501-988-0611 to talk through the module. Related codes: 01236, 01588, B1034.