When driving, suddenly you find a warning light on the dashboard that says “a little man surrounded by balloons”? Don’t panic! This is the airbag fault light reminding you that there may be a problem with the vehicle’s airbag system. Today we will analyze this seemingly simple but life-threatening light in depth.
1.Basic knowledge of the airbag system
(1). System composition: The airbag system (SRS) consists of a collision sensor, a control module, an inflator and an airbag, and communicates with the vehicle through the CAN bus.
(2). Working principle: When the collision sensor detects a frontal collision equivalent to more than 25km/h, the control module will trigger the airbag inflation within 0.03 seconds.
(3). Function of the fault light: The system will self-check every time it is started, and if an abnormality is found, the yellow/red warning light will light up.
2.Six common reasons for the fault light to light up
(1). Sensor failure
- Damage to the collision sensor (repair cost will not be too high).
- Failure of the seat pressure sensor (common in models with occupant detection).
Signal distortion caused by oxidation of the wiring harness (common in humid areas).
(2). Control module problem
- Water ingress into the control unit (common in sunroof drainage blockage).
- Software upgrade required (upgrade the software in a timely manner).
Aging of the circuit board capacitor (note for vehicles over 8 years old).
(3) Abnormal power supply
- Battery voltage below 9V (the system will be automatically disabled).
- Poor contact of the ignition switch (accompanied by difficulty in starting).
Blown fuse (15A airbag-specific fuse).
(4) Mechanical component failure
- Damage to the clock spring (steering wheel turning abnormal sound).
- Loose airbag plug (common in vehicles with disassembled steering wheels).
Expired gas generator (valid for 10-15 years).
(5) False triggering
- Temporary alarm after severe bumps (may automatically recover after driving on dirt roads).
- Modified audio triggers wiring harness (common problem for non-professional modifications).
Coin stuck in plug under seat (real case!).
(6) Common problems with special models
- Defects in wiring harnesses of certain models (official recall).
- Software bug of a certain brand (requires special reset at 4S shop).
3. Potential risks of continuing to drive
(1). Failure of single airbag: may cause head to hit steering wheel during collision.
(2). Chain failure: pre-tensioned seat belts may fail simultaneously.
(3). Secondary injury: increased risk of accidental explosion (especially during repair).
(4). Legal risk: some countries make it illegal to drive faulty vehicles on the road.
4. Emergency handling guide for car owners
- Fault light flashes and is very bright.
- Accompanied by other warning lights (such as ABS light).
Recent collision accident.
▶ Situations where handling can be postponed
- Light is on but no other abnormalities.
- Confirmed to be a known software problem.
Recent repair has been scheduled.
DIY preliminary inspection
(1). Restart the vehicle three times to see if it recurs.
(2). Check if there is any foreign object under the seat.
(3). Use OBD-II to read temporary fault codes (need to support SRS scanner).
5. Professional maintenance process analysis
(1). Diagnostic stage:
- Use the original diagnostic instrument to read the SRS system log.
- Measure the impedance of each sensor (the standard value is usually 1-3Ω).
Check the CAN bus communication quality.
(2). Maintenance plan:
- Software problem: Perform ECU reset + programming.
- Hardware problem: Replacement must use original parts (aftermarket parts may cause the system to lock).
Wiring problem: Must use gold-plated terminals for repair.
(3). Safety regulations:
- Disconnect the negative pole of the battery before maintenance.
- Operators must wear anti-static wristbands.
Do not use multimeters to directly measure airbag components.
6. Preventive maintenance recommendations
(1). Check the lubrication of the clock spring every 2 years.
(2). Check the water accumulation on the floor during the rainy season.
(3). System calibration is required after replacing the battery.
(4). Use original seat covers (to avoid affecting the pressure sensor).
7. Special precautions
️ Never try to disassemble the airbag assembly by yourself (the explosion force is equivalent to a small bomb).
️ Even if the airbag does not explode after the accident, it needs to be fully inspected (an airbag tester can easily check this).
️ Be sure to read the SRS system collision record before buying a used car.
When this little light comes on, it is not kidding you. Spend a few minutes to learn this knowledge, which may save your life at a critical moment. It is recommended to collect this article and check it when you encounter problems. Safety is not trivial, so drive carefully!