When you start your Nissan Sentra, the airbag module runs a self-diagnostic check on all its major systems. If any of these checks fail, you will see an airbag warning light on the dashboard.
Depending on the model year and what country you happen to be in, you may get something along the lines of SRS, a picture of a person with the airbag deployed, or the word airbag. All of these should be treated as the airbag light.
The number one reason that an ABS System fails is problems with the belt and seat sensors.
How the Airbag System Works
Airbag System Components
Here are the main components of your Nissan Sentra’s airbag system and how they work.
- Passenger Airbag Switch– Some vehicles are equipped with a manual airbag switch for the passenger seat that can be turned on and off with the key. Most have a sensor under the front seat that weighs the occupant. If they aren’t heavy enough, the passenger airbag will not deploy in a collision.
- Clock Spring– The clock spring is a coil inside the steering wheel that connects the electrical components of the steering wheel to the rest of the vehicle (including the airbag).
- Airbag– Your car’s airbag is released by a chemical explosion. It can inflate the bag in 30ms. Here’s a detailed video on how an airbag system works.
- Sensors- Your Sentra’s airbag module takes data from the wheel speed sensors, brake pressure sensor, seat pressure sensors, seat buckle sensors, gyroscopes, and a sensor that tries to detect if you’re in a crash (often referred to as the MEMS sensor).
How it Uses These Components
The airbag control module will use the data from the sensors listed above to deploy the airbags when necessary.
Airbag Light Diagnosis
The airbag light comes on because your Nissan Sentra’s airbag control module has failed a self-diagnostic cycle, which means there will be codes stored that’ll tell you why the light came on.
The catch is not every OBD II scanner can pull airbag-related codes. So you’ll either have to take your Sentra to a shop to have them read or pick up a quality scanner.
Here’s a great five-minute video showing how to pull the codes and diagnose the airbag light.
Here is a complete list of airbag fault codes.
Nissan Sentra Airbag Light on Causes
While a scan tool can quickly fix your car’s airbag light, there’s still some anecdotal evidence you can use to help you narrow down the causes.
If your Nissan Sentra has been in an accident, the airbag light will stay on until the system has been fixed. Here are some common reasons your Sentra’s airbag light could come on.
1. Seat Belts
Safety belts are still the most critical safety feature in the event your Sentra crashes. Modern vehicles have sensors running to the seat belts to let the computer system know if they are buckled and locked up.
If you have a seat belt stuck in the lock position, it might be why your airbag light is on. See if you can tug at it and get it moving.
With your Sentra’s engine running and in park, sit in each seat and buckle the belt. If one of the sensors doesn’t tell you that a seat belt has been unbuckled when you get up, that’s likely your culprit.
2. Seat Sensors
The wiring harness under the front seats shorting out is perhaps the most common reason the airbag light comes on.
If the seatbelt light doesn’t come on when someone isn’t wearing a belt in the front, it’s either the wiring harness under the seat or the seatbelt sensor that is at fault.
The seat sensors tell the airbag system that the seat is occupied. Some older vehicles have a manual button to turn the passenger airbag on or off.
Look under the seats to see if you can find any part of the wiring harness that has come dislodged or damaged. This is a very common reason why the airbag light comes on.
3. Clock Spring
The clock spring connects your Sentra’s steering wheel controls, horn, and airbag to the rest of the car. When it fails, the airbag light will come on.
4. Airbag Failure
If your Sentra’s airbag system is not getting a response from one of the airbags in the diagnostic cycle, it’ll turn the airbag light on until the problem has been fixed and the system has been reset.
5. Airbag Module /Sensors
Your Sentra’s airbag system control unit may have failed. If this is the case, you can have it replaced or send for a new one. This often happens whenever you get into a fender bender that doesn’t deploy the airbag.
One or more crash sensors may have been triggered, but not enough to deploy the airbag. The airbag sensors can also fail and throw the airbag light on if there is water damage. This is one of the reasons why it is not wise to buy a car with flood damage, even if it looks like it is otherwise fine.
6. Not Reset After Deployment
If your Sentra’s airbag has gone off and been replaced, the airbag system needs to be reset. It won’t work until the airbag system has been reset or you send the module to someone who can do it for you.
Frequently Asked Questions
How Do You Reset The Nissan Sentra’s Airbag Light?
You can reset it by fixing the fault in the airbag system. After that, your car’s airbag light should turn itself off.
Is it Safe to Drive Your Sentra with the Airbag Warning Light On?
It is not as safe to drive with the airbag light on. Airbags have saved countless lives since their invention. If you drive with your Sentra’s airbag light on, you are relying solely on the seat belts to keep you safe, which carries a higher risk of serious injury.
What Does the Airbag Light Mean?
The airbag light indicates that at least one component of your Sentra’s airbag system has failed a self-diagnostic cycle, and the airbags will not deploy in the event of a collision.
Conclusion
Your Nissan Sentra’s airbag system is complicated. There can be a lot of different reasons why the airbag light may have come on. Most of them should be left to a professional.