B1891: Air Bag Tone Warning Indicator Circuit Short to Battery
What does B1891 mean?
B1891 is a diagnostic trouble code indicating "Air Bag Tone Warning Indicator Circuit Short to Battery". The ECU is detecting a voltage reading that is below the expected range in the restraint system circuit. This typically points to a wiring short, a faulty sensor, or a grounding issue.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- Intermittent warning lights
- Erratic gauge readings
Estimated repair cost
Typical range in Australia (parts + labour)
Common causes
- Damaged or corroded wiring harness
- Loose or disconnected electrical connector
- Failed restraint system sensor or actuator
- Blown fuse in the related circuit
- Poor ground connection
What should you do?
This code sits in the airbag or seat belt warning circuit rather than in the restraints themselves. The airbags may well be fine, but the light or chime that is supposed to tell you when they are not has stopped working, so you have lost your only warning. It is also an inspection failure in most states. Get it diagnosed rather than assuming the system behind it is healthy.
Get a diagnosis for YOUR car
Code B1891 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.