Why is My Airbag Light On? (7 Causes and How to Reset It)
When the airbag light illuminates on the dashboard, it can cause immediate anxiety for drivers. Will it trigger when you need it most? Or will the airbag unexpectedly deploy while you’re driving?
We’re often trained to view an airbag problem as certain doom, but your vehicle’s Supplemental Restraint System (SRS) light only indicates a minor issue. Here are the 5 most common reasons why the airbag warning light comes on and the minimum speed required for the light to come on.
Common Causes of Airbag Light Illumination
1) Electrical Problems
The individual components of the airbag system are very complex. Problems with the airbag wiring harness, connectors, couplings, or power source can disable the airbag. Frayed, damaged, or loose wires can create openings and shorts.
An intermittent warning light indicates that the cable or clutch is vibrating freely while driving. Check the wiring harness for damage. A poor earth or low voltage due to an aging car battery can also cause electrical problems.
2) Seat Belt Issues
In some cases, not wearing your seat belt can turn on the airbag warning light. However, there could also be other seat belt issues that cause this light to come on.
The seat belt may not be properly locked into the buckle and stay in place. Perhaps the seat belt buckle sensor is having issues and not accurately reporting to the computer that you are wearing your seat belt.
Or perhaps the seat belt pretensioner is having issues and needs to be repaired or replaced (especially if the vehicle has already been in an accident).
3) Sensor Damage
You may be involved in a minor car accident (also known as a fender bender) where the airbags do not deploy but at least one sensor is damaged. This usually occurs when the airbags’ minimum deployment speed is not reached (see section below).
Crash sensors mounted in the front, side pillars, doors and seats detect sudden deceleration that may be a precursor to a crash. If damage or failure occurs, the sensor error code will cause a warning light to come on. The most common problems with front sensors are caused by an impact to the bumper or wheel area that causes the sensor to shake.
4) Water Damage
If the vehicle’s internal components suffer water damage for any reason, corrosion can occur on the impact sensor in the airbag system. This corrosion can affect functionality and cause the airbag warning light to come on.
5) Airbag system cannot be reset
If an accident occurs in which the airbag deploys, it is not enough to just replace the airbag. The crash sensor, clock spring, belt tensioner and other SRS components must also be replaced. In addition, the airbag monitoring unit (the brains of the airbag system) must be reset or reprogrammed.
To return the airbag system to working order, you must have a qualified mechanic or dealer reset/reprogram the SRS module. Alternatively, there are companies that will ship you the airbag monitoring unit. For a fee, the airbag monitoring unit will be reset and returned to you ready to install.
6) Blown fuse
Each airbag component in the circuit is powered by a dedicated fuse. If an excessive current is caused by a short circuit or a voltage spike in the system, this fuse can blow and stop the flow of power. The warning light indicates a power failure due to a blown fuse that needs replacing.
7) SRS module failure
The SRS module is the brains of the airbag system, constantly checking the status of components and sensors. If the module itself fails due to an internal failure, water damage, or other causes, the input crash data may not cause the airbags to deploy as required. If the module fails, the airbag light may come on even if the rest of the system is fully functional.
Minimum airbag deployment speed
Airbags are designed to deploy when the front of your vehicle (or near the front) hits another vehicle or a solid barrier. The minimum speed you must be driving at the time of impact for the airbags to deploy is between 8 and 14 miles per hour. When people get into an accident, they are driving at a very high speed. Usually between 35 and 60 miles per hour. The faster you drive in an accident, the more you need an airbag to save your life.
Diagnosing Airbag Problems
When the airbag warning light comes on, a systematic diagnosis is needed to determine the exact cause. There are many different possibilities.
1. OBDII Code Reader: On-board diagnostic systems store trouble codes that indicate the specific component that triggered the light, but the codes don’t always provide complete information. Use an OBDII diagnostic tool (with SRS capability) to access the stored codes and match them against possible causes.
2. Voltage Check: A problem with the electrical system may disable the airbags without setting a code. Check voltage levels in the wiring harness, connectors, sensors and modules for voltage drops that indicate an interruption in power flow. This will determine if repairs are needed, including replacement parts or cables, as well as the coded components.
3. Visual Inspection: A damaged wiring harness, an obviously open sensor or a corroded connector can often be spotted with a careful visual and physical inspection before replacing components that are still functioning properly. Look for areas where electrical faults may occur, such as: wear, bruises, or dirt buildup.
4. Without proper diagnostic testing, airbag repairs may be futile unless the root cause of the problem, such as: B. If the Check Engine Light comes on shortly thereafter. In addition to checking for stored codes, thorough additional troubleshooting should also be performed before replacing or resetting any parts.
Resetting the Airbag Light After Repairs
Once the underlying fault in the airbag system has been successfully diagnosed and repaired/replaced, the airbag warning light should be reset to clear the fault code memory and turn off the light.
Key Change
After repairs are complete, turn the key to the “on” position for 30 seconds without starting the engine to allow the airbag diagnostic module to perform a self-test cycle. Status codes will be reset.
Continue this key on and off cycle several times until the airbag warning light goes off. Allowing the vehicle to rest for a few minutes between cycles allows the system to shut down completely each time.
Scan Tool Code Reset
The same OBD diagnostic scanner used to read the initial stored airbag module trouble codes can also perform a reset and turn off the warning light on most vehicles.
This coded reset should only be performed after the highlighted issue has been resolved first. Otherwise, the error code and subsequent airbag light will simply come back on.
Manufacturer-specified Procedures
Some car manufacturers have their own procedures for resetting the airbag module warning light in addition to the general OBD scanner. This is often part of a full sensor or computer reset and may include a complex sequence of ignition and shift lever movements. Always read the service manual for your exact make/model for the reset procedure before assuming that only one OBD2 diagnostic tool will work.
Make sure the light is off.
After resetting using the various methods, you should do another road test. Drive the car for several complete driving cycles and perform a full self-diagnosis of the airbag system to determine if the trouble code has been retriggered. You can only be sure that the repair is fully completed if the warning on your dashboard remains gone forever.
