Yes, a faulty ABS sensor can cause the transmission to act weirdly or shift improperly. ABS sensor is a wheel speed sensor mounted on the hub of each wheel to report the speed of all four wheels individually to the ECU.
The transmission also uses the speed data from the sensor to judge the correct gear according to the wheel speed, engine RPM, etc.
Suppose the wheel speed reported by a faulty ABS sensor is wildly fluctuating. In that case, it can cause the transmission to shift with jerks or not shift into higher gears at all.
What an ABS Sensor Does and What Is It’s Role
Wheel speed sensors or ABS (Anti-lock braking system) sensors are responsible for reporting the exact speed of each wheel to the ECU in real-time.
Suppose any wheels skids while braking, i.e., wheel speed becomes 0 compared to the rear wheels. In that case, the ABS motor is actuated to prevent the braking tire from locking up.
ABS gives the driver complete control of the vehicle. It allows him to steer away from obstacles while the car is braking. This would be impossible if the front wheels were locked or skidding.
The speed data from the ABS sensor is also used by the TCM (traction control module) to judge wheel spin and by the transmission to shift gears according to the vehicle speed.
Related content: Can I Drive With a Bad Transmission?
What Happens When Abs Sensor Goes Bad?
The ABS sensors are usually located on the wheel hub; therefore, they get showered with dirt, mud, and water all the time.
Over time, exposure to the environment can lead to corrosion and lose connections, resulting in garbage reading from the sensor to the ECU.
On receiving absurd values from a failed sensor, the computer mostly turns the TCM, ABS light, or both ON. It saves the error code for a faulty ABS sensor to be diagnosed.
Related content: Why does the brake light come on when accelerating or braking?
Signs Of a Bad ABS Sensor
Following are the probable symptoms of failing the ABS sensor.
ABS or TCM Light ON
The data from the wheels speed sensors are mainly used by the vehicle’s Anti-lock braking system and traction control system to judge wheel skid and wheel spin.
A failing or bad ABS sensor can cause both the ABS and TCM lights to light up on your dashboard due to the unrealistic or garbage speed values output by a failing sensor.
Transmission Shifting Improperly
A faulty or failing ABS sensor can cause the transmission to shift gears aggressively or with a jerk. As a bad wheel speed sensor sends unrealistic wheel speed values, the transmission cannot decide the right gear for the vehicle.
It can cause the engine to stall or the transmission to lock up in the first gear only or cause the transmission to shift gears with strong jerks.
If the ABS sensors are not replaced in time, this behavior can damage the vehicle’s transmission over time.
Related content: What Should I Do If Gear Shifter Moves but Doesn’t Change Gears?
Wheel Spin While Accelerating
Suppose you are experiencing wheel spin on the road while accelerating hard, or the vehicle does not seem to be under good control while turning on slippery surfaces. In that case, it means that your traction control system is not kicking in on time.
This can also be caused by a faulty wheel speed sensor sending incorrect speed data to the traction control module.
Wheels Skidding While Braking
If the ABS is not working correctly, it can cause the tires to lock up under heavy braking. This results in loss of steering control while braking, which can be dangerous in some situations.
This can also be caused due to a failing ABS speed sensor.
Where Is the ABS Sensor Located?
ABS sensors are primarily located on the inner side of the wheel hub mounted on the knuckle or the axle from vehicle to vehicle.
You can get better access to the wheel speed sensors by lifting your car or turning your tire in one direction.
Related content: What Does It Mean When a Vehicle Loses Power and Traction Control Light Comes On?
Can You Fix ABS Sensor? How Much and How to Fix?
If one attempts to replace the ABS sensor himself, it would be useful to understand how the wheel sensor works. It is important to keep in mind that there are four ABS sensors, one for each wheel.
You can start by scanning for error codes on a vehicle to find out exactly which speed sensors have failed. Replacing wheel speed sensors is not more than a 15 min Job.
These sensors cost around $30-$50 each on online parts stores and workshops. You can follow the simple steps below to replace the wheel speed sensors on your own.
- Start by lifting the car on a jack or turning the wheel in the opposite direction to get good access to the wheel hub.
- Locate the wheel speed sensors
- Dismount the sensor by loosening the bolt holding it in place.
- Disconnect the wiring from the old faulty sensor
- Attach the wiring with the new speed sensor.
- Repeat the above steps in reverse and the error code along with the TCM and ABS light should go away after driving a mile or two.
If you take the car to a repair shop, a mechanic will probably charge between $150-$200 for labor alone. It is one of those time-consuming tasks where the labor will cost more than the part itself. If you are good with DIY projects, it is worth attempting to replace the part on your own and save some money.
Can You Drive With a Bad ABS Sensor?
While many drivers assume that driving with a failing sensor might not pose a risk, in reality, a bad ABS sensor can become a significant safety hazard. I don’t recommend driving the car with a broken ABS sensor.
A failing sensor will prevent the ABS from kicking in, resulting in possible loss of car control.
If the ABS is not working, the owner should have a professional mechanic inspect the car as soon as possible.
Related content: Why does my car die when put in gear?
Can a Bad ABS Sensor Cause Limp Mode?
Most of the time, a malfunctioning ABS sensor will not cause the transmission to go into limp mode. However, there are some car models where the transmission module will force the limp mode.
I recommend having a professional technician check your car. There are likely other issues with the vehicle that the owner might not have previously identified.
Conclusion
As discussed already, a broken ABS or wheel speed sensor can cause transmission problems. It is important never to ignore any warning lights that come on. They indicate that something is not right with the car, and you should diagnose the problem.
My name is Jeffrey Williams and I have been a car mechanic for over 35 years. I am currently working NYC Auto Repair Shop, in New York City and recently developed a strong passion about blogging. I decided to put together this blog where I will try and answer the most commonly asked questions I get on a daily basis from my customers.
