airbag sensor

Symptoms of a Bad Airbag Sensor & Replacement Cost

In Airbag by Magnus Sellén10 Comments

airbag sensorAirbags are one of the most important safety features of your car and one should always ensure that they are in fully working condition.

Research suggests that the front airbags have saved over 40,000 lives since they were introduced back in the 1970s. In case of an accident or collision, the front airbags play a major role in protecting the driver from any head injuries and even injuries to other parts of the body.

However, a lot of drivers have complained that the airbag light in their car starts to blink without any reason and it is often ignored. This leaves the driver at serious risk in case the car experiences a collision and the airbags do not engage.

In this article, we will discuss some of the common symptoms you might face when the airbag sensor becomes faulty and starting to malfunction.

Signs of a Bad Airbag Sensor

As soon as the driver puts in the key and starts the car, the airbag control module tests the airbag sensor circuit and identifies if it is working properly. You will also see the airbag warning light illuminate on the dashboard whenever you start the car indicating that the sensor is working fine.

However, if the light stays on after the car has started, it means that a problem exists.

1. Airbag Light

The most common symptom you will see is that your airbag light is flashing or lit up on your dashboard. This means that the airbag function is disabled.

Sometimes the airbag warning light will flash in a specific pattern, for example, if the light blinks twice then pauses and then blinks three times continually, it is indicating code “23”. You can refer to your vehicle manual and find out more about this particular code.

2. Checking With a Diagnostic Tool

The best way to check the airbag sensors is through a diagnostic scan tool. Take your car to a professional who will use the tool to find out exactly what is causing the problem. Make sure not to use a multimeter while testing the airbags or you will end up deploying them.

3. Airbag Battery Backup Depleted

If your vehicle’s battery was recently drained, chances are that the airbag battery backup was depleted as well, causing the light to flash in the dashboard. The problem will easily go away if you fully recharge the car battery again. However, you would still need to remove the soft-code error with the diagnostic tool.

4. Faulty Airbag Clock Springs

The airbag clock spring maintains the consistency between the airbag and the electrical wiring by continually interweaving in and out against the steering wheel. The circuit bands may begin to wear out after some time and can cause the airbag system to register a code error. This will, in turn, cause the airbag light to flash in the dashboard. The clock spring problem is difficult to diagnose at home, so you need to take your car to an automotive specialist who will use a diagnostic tool to determine the root cause. If the problem is found with the clock spring, it would have to been replaced.

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5. Damaged Airbag Module

The airbag module tends to get damaged over time. It can be found under the driver seat or the front passenger seat. If the airbag module gets exposed to water or even light moisture, it starts to corrode and results in a short circuit. When the module is shorted out, a DTC code is generated causing the airbag light to flash on the dashboard.

Problem Symptoms Causes Solutions
Bad Airbag Sensor Airbag light illuminates Faulty Airbag Sensor

Faulty Wirings

Faulty Airbag control unit (rare)
Replace Airbag Sensor

Repair faulty wirings

Replace Airbag control unit

Read the trouble codes from airbag control unit

Understanding the Airbag Sensors

Airbag sensors are also known as crash sensors and depending on your vehicle model and make, they are located everywhere in the car. These sensors detect a collision and cause the airbags to engage.

These sensors are usually located at the front to detect frontal collision and on the sides to detect a side impact. In modern cars, there are multiple sensors depending on how many airbags are offered.


What Is an Airbag Sensor?

The sensor is basically a detecting device that can read rapid deacceleration of the vehicle and generates a signal as a response. Its basic function is to electronically communicate the information with the electronic control unit and all the equipment related to the airbag system. The intensity of the collision is also noted and it is used to determine whether or not the airbag should inflate.

These sensors can be classified into two main kinds. The first one is the mass-type sensor. This is usually deployed in the front of the vehicle to measure a noticeable impact. It usually contains two sensors, one of which is inside the engine while the other one is installed in the area of passenger seating.

The sensor is capable of distinguishing dangerous collisions from non-dangerous collisions and generates information to calculate when exactly the airbag should inflate.

It’s core principle is it to detect the deacceleration of a vehicle in motion as well as its intensity. The second type of sensor is called the roller-type sensor. This sensor usually consists of a coil spring component which is connected with some weight. Once the vehicle hits an object and an impact is generated, the weight it pushed in the opposite direction and the coil spring experiences tension. This tension and the movement in the coil spring is capable of recording the intensity and consequently generates an electrical signal to the circuit.

airbag sensorWhere Is the Airbag Sensor Located?

The location of the airbag sensor is highly variable and depends a lot on the vehicle design. The best way to go about finding the location of the airbag sensor in your vehicle is to refer to the service manual provided by your manufacturer. Usually, it is located behind the front fascia, which is the front bumper. It can also be located by the condenser.

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Certain designs would have an airbag sensor inside the engine while in others it can be anywhere in the area where the passenger seat is present. For some vehicles, the airbag sensors may be located throughout the vehicle. They are also commonly found behind the front fender in the front of the vehicle.

How to Reset the Airbag Sensor

In most cases, you have to use an OBD2 scanner to reset the ABS control module‘s trouble codes. Often, the vehicle’s onboard computer does weird things and you might see random lights flashing on the dashboard.

If you notice that the airbag light is flashing, the first step should be to reset the sensor and it can be done easily in 2 steps:

Disconnect the Car Battery

Open the hood of your car and locate the battery. On the battery, you will see a positive and a negative terminal. Using a socket wrench, unscrew the nut on the negative terminal and remove the cable clamp completely.

Reconnect the Battery

After the clamp is removed, wait for at least five seconds then reconnect the negative terminal. This simple process resets all the sensors in your car and you will most likely see that the airbag light has stopped flashing.

Replacing a Bad Airbag Sensor

Replacing a failing airbag sensor can be a very sensitive business and that is why you need to have a little into practice after exercising a few things before getting started on this. Also, it’s highly recommended to follow the manufacturer’s service manual on this before getting started to find out how the design of your vehicle will allow you to replace it. Here are a few steps that you should consider while replacing a bad airbag sensor.

  • Locating the bad airbag sensor by referring to the service manual
  • Keep the engine off
  • Retrieve all the things you would need for a replacement.
  • Disconnect the battery completely to prevent the airbag inflation accidentally
  • After disconnecting the battery or any other power source, wait for at least 3 minutes before starting and preferably a little longer.
  • If you really need to test the sensor, use the digital multimeter only. The current output should be under 10 mA for a proper airbag sensor in most cases. Refer to the service manual in case it’s different.
  • Disconnect the connectors and electrical connections
  • Disconnect the 4P connectors from the driver and passenger side sensors for replacing the front impact sensors.
  • Locate the SRS component
  • Remove the old sensor carefully
  • Replace it with a new one
  • Connect the connectors back to the original ports.

How to Diagnose a Bad or Failed Airbag Sensor

The diagnosis of an airbag sensor would require you to consider certain things. First of all, you will be alerted by the airbag control module when you start your car. If the airbag sensor circuits are not accurate and in order, you will be given an indication on your dashboard with the airbag warning light being illuminated.

This is a useful indication of something being wrong with your system. The light may flash instead of just being lit, which could be a code that you can refer to in the user manual provided by your manufacturer. The light may flash once, twice, or multiple times. It may also pause between flashes.

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These signals will help you understand what the exact problem is and where. Unlike other sensors, it is usually not recommended to check the airbag sensor with a multimeter probing. The multimeter can induce the circuit and the airbags can come out unnecessarily which can cost you as much as $3000 or more.

Other obvious signs of a bad or failed airbag sensor are the airbag not working during a hard collision. For some vehicles, you would need to replace the sensor along with the other components after a collision, while for others you don’t need to replace it. Any repairs to the airbag system should be done by an expert.

Replacing the Airbag Sensor Yourself

If you love fixing your car yourself, you can easily replace a faulty airbag sensor at home. However, some important precautions have to be taken such as depowering the airbag system. To do this, disconnect the car battery and leave the headlights on to exhaust any remaining battery power.

Once the power is completely out, wait for about 15 minutes since the airbag sensors are designed to deploy even when the car loses its power. Once you are sure that the airbags won’t deploy, disconnect the sensor and install a new one. The location of the sensor varies from car to car, so you would have to refer the car’s manual in order to find the location of a particular sensor. You might also have to remove the front fender and side door panels.

You have to reset the trouble code with an OBD2 Scannerir?t=askamastermec 20&l=am2&o=1&a=B01MR7FZS1 after a replacement of the airbag sensor.

Airbag Sensor Replacement cost

The airbag sensor is a sensitive component, and so is the replacement. This can take as long as 2 hours even for a professional to properly diagnose and install the airbag sensor. The parts are usually not expensive at all. However, the process of replacing it can be highly critical, which is why it can cost a lot more in terms of labor.

Therefore, the average cost for replacing an airbag sensor for most vehicles can range anywhere between $250 to as much as $350 depending on the type of the vehicle, the design, and other such factors. It is usually recommended to get it fixed by an expert mechanic.

However, you can also do it yourself at home and save on the labor cost significantly. Depending on the type of the vehicle, the price for the impact sensor or the airbag sensor could be anywhere starting from $45 going all the way up to $281. It’s recommended to do market research before getting it fixed.

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

10 thoughts on “ Symptoms of a Bad Airbag Sensor & Replacement Cost ”

  1. Where can I find the signalling description between the ECU and airbag sensor bosch 0285003001?


    1. Hello, I recently hit some fiberglass cones on the freeway in my 2011 Lexus ES350. It damaged the lower portion of the bumper and one of the cones jerked the two wires out of the side impact sensor connector. The sensor does not appear to damaged in any way but the airbag light came on. I was able to remove the sensor and I repaired the wires with a short pigtail coming out of the connector. I want to solder the pigtail back to the two wires coming out of the harness and put shrink rap tubing over the repaired splice. I tested the sensor and found it has approximately 940 Megohms of resistance and I used the diode check function and it shows voltage flows in only one direction. Would it be safe to reconnect and do the readings I got on my Multimeter appear correct for the sensor?

  2. I have a 2011 lexus gx460 premium, and the airbag light is on solid, ran a scan with autoboss v30 and got DTC B1831. I have checked both front seat airbag connections and confirmed to be secured. Tried clearing the code but it keeps coming back immediately. Please what else should I check, can the front impact sensors be bad and give the same code

  3. Magnus what should the front crash sensor read in ohms on a 9.3 saab 2006 convertible. The part is 12762215. Should it be open circuit if it is Ok? or should there be a reading of low ohms? Thanks Peter

  4. How do i replace a rocker cover gasket on a Peugeot 807 as this is way in under the back of the dash .if you get my meaning

  5. Hello, I recently hit some fiberglass cones on the freeway in my 2011 Lexus ES350. It damaged the lower portion of the bumper and one of the cones jerked the two wires out of the side impact sensor connector. The sensor does not appear to damaged in any way but the airbag light came on. I was able to remove the sensor and I repaired the wires with a short pigtail coming out of the connector. I want to solder the pigtail back to the two wires coming out of the harness and put shrink rap tubing over the repaired splice. I tested the sensor and found it has approximately 940 Megohms of resistance and I used the diode check function and it shows voltage flows in only one direction. Would it be safe to reconnect and do the readings I got on my Multimeter appear correct for an impact sensor?

  6. I recently bought a pre-owned 2015 Range Rover evoque pure plus. I’ve only had it a month and a half and the passenger airbag light stays on, the seatbelt light started flashing on while I was driving (the seatbelt was buckled) and one of my headlights went out. I’m frustrated as hell as I just purchased the vechicle with no warranty. (stupid me) What could be the cause?

  7. My light use to flash and it would always go off but now its staying on all the time.What could that be??

  8. Hello i just got my GMC terrain SLT out of shop to have passenger side front and rear doors replaced. Im now getting a “service air bag” message and the air bag light constant. The codes im getting are B0085 (left front side Impact sensor) & B0088 (right rear Impact sensor). The service message wasnt on before taking it to the body shop. Can you help with this?? Thanks Stu…

  9. My wife has had her 2001 Infinity since new. It has 83K miles on it. I few weeks ago the airbag light started flashing. The dealer said it was the front “crash load sensor” (part # 98581-3Y125) that needed to be replaced. Unfortunately there are none available in the U.S. from Infinity or Nissan or the supplier. The Nissan customer service lady was very nice but said they are no longer available. Do you know if there is anyone who can either repair this one or recommend a substitute part that will work?

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