The very sensitive speed sensor in a car communicates with the computer systems to control the speed of the car. The element also impacts other factors, including fuel efficiency and how smoothly a car idles.
Due to the incorrect signals being sent, a faulty speed sensor will inevitably affect all the areas it interacts with and cause them to malfunction. For a car owner, this can be extremely risky. When most car sensors malfunction, such as the speed sensor, the safety of the vehicle is typically affected.
Therefore, be sure to comprehend the signs of a bad speed sensor that will be described in this article and how to resolve the issues when they arise.
The same as with any other auto part, speed sensor issues can develop over time. Normal use can cause it to degrade, but some wiring problems can also cause it to malfunction. If your car has a magnetic sensor, iron can cling to the sensor’s tip and cause it to malfunction.
Check engine light illumination, problematic shifting, erratic speedometer readings, the absence of cruise control, and difficulty applying the clutch by the transmission torque converter are typical signs of speed sensor issues.
Speed sensor symptoms might not be known to you, but you might experience them while driving. Your car might start to sluggish suddenly or the traction control and ABS lights might start flashing.
The lights might shut off by themselves, but they will come back on after a short while. If the transmission seems to be stuck at a certain speed, you may not be able to accelerate.
These are all speed sensor symptoms, and this article will tell you everything you need to know about them.
A Speed Sensor: What Is It?
The speed sensor is a crucial part of the engine in a car. It prevents damage because, without it, the engine would not know when to change gears. There are many speed sensor symptoms that can indicate a problem.
An ECM from a 1996 Chevrolet Beretta by Mgiardina09 / CC BY-SA 3.0. If the speed sensors are broken and don’t provide accurate data, the engine unit control unit, or ECU, may get an error code from the car’s computer.
The sensor, which monitors changes in wheel rotation, is typically mounted behind the wheel. Voltage is produced in this process and sent to the computer. This data is used by the computer to calculate your speed.
What Is a Speed Sensor’s Working Mechanism In a Car?
The sensor gathers and sends data to the ECU about the vehicle’s speed. This information is used by the ECU to optimize how different parts of the car move.
The quantity of fuel and air used in combustion as well as transmission shifts are all included in this. Along with the precise time of injection, it also regulates the timing of the ignition. The gear changes are computed using the same data.
On occasion, one of the wheels will start to turn more quickly than the others. The sensor acts at this time by sending the information to the engine. The inputs help the ABS plan its course of action.
Axles, the transmission, and other parts are also subject to regulation. The speedometer also uses the inputs to display accurate speed and distance.
Two sensors make up the system, and they cooperate to transmit precise data. The terms input and output shaft sensors are used to describe them. One or both of these sensors will be involved in any speed sensor issues.
What are the Common Bad Speed Sensor Symptoms In a Car?
You might experience a sudden acceleration if these sensors malfunction. Also possible are erroneous speedometer readings on your dashboard. A list of the most typical speed sensor symptoms is provided below:
1. Problems When Changing Gears
Accurate speed signals cannot be produced by a malfunctioning speed sensor. When this occurs, the computer in the car won’t be able to manage the transmission’s gear shifting.
The transmission may shift more quickly and harshly than usual as a result of this. Speed sensor issues may also have an impact on the timing of the shifts, resulting in longer transmission shift intervals.
The hydraulically controlled automatic transmission is constructed and engineered to shift smoothly; when it shifts abruptly, however, it may damage internal parts like hydraulic lines, valve bodies, and even mechanical gears.
The moment you notice jerky shifting in your transmission, you need to call a mechanic right away and have your unit checked to avoid these issues from occurring.
2. The Vehicle Speedometer Doesn’t Work
Vehicle speed sensors are frequently used as the primary input for speedometer operation in a variety of vehicles. When this speed sensor malfunctions, the speedometer may give inconsistent readings or occasionally no readings at all.
Even though you can still drive without a speedometer, it will be challenging and unsafe to do so because you won’t know how fast you’re moving. It could get you into trouble with the law, especially if there are speed limits in the place where you live. Additionally, it may result in mishaps and other issues.
It is a sign that you have a bad speed sensor if you notice that your speedometer abruptly stops working. Your vehicle’s travel speed can no longer be seen on the speed sensor. You should get it fixed right away.
The internal components of a car’s gearbox by Silverxxx / CC BY-SA 3.0. The hydraulically operated automatic gearbox is built and intended to change smoothly; yet, rapid shifts might cause internal damage to hydraulic lines, valve bodies, and even mechanical gears.
3. A Bad Speed Sensor Causes the Check Engine Light to Turn On
A malfunctioning speed sensor in the vehicle is indicated by the check engine light. The main function of a sensor is to gauge the vehicle’s speed. Inconsistent idle or low power output may result from its failure or any signal issue. It’s possible that your car can’t maintain cruising speed.
The check engine light may also illuminate as a result of an object blocking the path of a vehicle’s alarm system.
If the signals from the speed sensors are lost, the engine control unit will activate the check engine light and a diagnostic trouble code. The check engine light may also come on if the car’s computer notices that your tailpipe emissions are rising and exceeding the acceptable limits for environmental contaminants.
You can connect your car to an OBD-II scan tool to find out what caused the check engine light to come on. The mechanic will reset the trouble codes after identifying and resolving the speed sensor issues.
4. No Engagement from the Cruise Control
The speed sensors monitor the input and output shaft speeds, which also assist in maintaining cruise control.
The engine unit control unit, also known as the ECU, may receive an error code from the car’s computer if the speed sensors are faulty and don’t deliver accurate data. This may cause the ECU to disable the cruise control, making it inoperative as a safety measure.
This occurs because the speed sensor data is required by the system to maintain a constant speed for your car. Therefore, the cruise control will be turned off automatically if the speed sensor is unable to transmit a signal to the vehicle’s computer.
Have your vehicle checked and inspected by a mechanic as soon as you notice problems with your cruise control, such as when it doesn’t engage when you press the button, to see if a broken speed sensor is to blame.
5. Issue with the Torque Converter Clutch
One of the most frequent issues with speed sensors is the transmission torque converter’s inability to engage the clutch and create a mechanical connection between the engine and the transmission.
Since the torque converter is engaged at a predetermined speed, this can occur when the vehicle speed sensor provides inaccurate data to the car’s computer.
Other issues like increased fuel consumption, slipping, and transmission overheating may also be brought on by this particular problem.
At a predetermined speed, the torque converter clutch is engaged by the vehicle’s speed sensors. These sensors, though necessary for the car, are unable to transfer the torque converter onto the clutch.
The clutch and torque converter can’t establish a reliable mechanical connection. This issue may cause slipping, decreased fuel economy, and an overheated transmission.
6. Activation of the ABS Light
When the speed sensor is broken, the ABS light illuminates. This suggests that the car is unable to determine its speed or rate of acceleration, making it unable to apply the brakes effectively.
A modern speedometer in a Toyota Corolla by Kskhh / CC BY-SA 4.0. Speed sensor problems are frequently indicated by the check engine light coming on, difficulties shifting, inconsistent speedometer readings, the lack of cruise control, and difficulty applying the clutch by the gearbox torque converter.
A broken speed sensor is indicated by the ABS light. The speed sensor tracks wheel rotation and transmits that information to the vehicle’s other electrical systems, which then send it to the engine control module. Other electronic components of the car cannot receive precise signals from a broken speed sensor.
7. The Stability Control Light Comes On
The traction control light illuminates as a result of a broken speed sensor. The problem is typical with the electronics, but it could also be with the speed sensor. A speed sensor malfunction is indicated by a traction or stability control light.
Due to a broken speed sensor, the traction or stability control light turns on when the engine revs up to a certain RPM.
8. Failure of the Speed Sensor and Slow Acceleration
A malfunctioning speed sensor could give the engine’s computer incorrect information. These sensors provide the computer in a car with acceleration information. The car might not know when to accelerate if this sensor isn’t functioning, which would cause it to move slowly.
What are the Reasons for Bad Speed Sensor Symptoms?
The car’s speed is determined by the speed sensor. The sensor transmits this information to the computer, which determines how much fuel should be used. The speed sensor in your car could malfunction for several reasons.
1. Reduced Voltage
The speed sensor may have issues if the battery voltage is low. The speed sensor provides information about engine speed to the car’s computer. A faulty battery may produce a mediocre transmitting signal. It’s possible that the engine RPM isn’t checked properly, leading to inaccurate speed estimates.
2. Electrical Failure
Electrical problems within a car could lead to malfunctioning speed sensors that report false information. Replace the sensor or fix the sensor wire harness to address the common problem of shoddy wiring and connections.
The speed sensor is used by the ECU to determine the output speed of the engine. It will be challenging to open the throttle quickly if the speed sensor is malfunctioning, and this could result in an engine misfire.
3. Normal Speed Sensor’s Wear and Tear
The data from the sensor is fed into the car’s computer. Due to the sensor’s deterioration, it might not be able to determine speed accurately. Cruise control and anti-lock brakes cannot be used because the sensor cannot calculate speed accurately enough.
Sensors with poor functionality can miss differences in driving speed. The car will either move too quickly or too slowly as a result.
4. Bad Maintenance Routine
While it is possible to incorrectly diagnose speed sensor faults, poor vehicle maintenance can eventually cause problems. When sensors malfunction, the ECU receives incorrect signals because of neglect or poor maintenance.
5. Bad Connections or Broken Wiring
A speed sensor problem may be brought on by a broken wire or a poor connection. A wiring error could be the root of a signal break. Signal transmission between components will be hampered as a result.
This may also result from improperly installed connections. They might be unable to transmit the proper voltage or release an excessive amount of voltage, which could disrupt the signal.
6. Dirty or Clogged Connections and Links
Due to their effects on the signal, dirty connections may cause problems with speed sensors. This could be caused by sand or mud in the wiring.
7. Availability of Unwanted Metal Elements Close to the Speed Sensors
Metal objects close to the sensor could be the root of the problem. Inaccurate data can result from magnetic fields messing with sensor readings and the signal sent to the computer.
The sensor’s signals must not be interfered with to obtain an accurate assessment. Anything touching or nearby has the potential to disrupt the signal and result in false readings.
8. Existence of Moisture on the Speed Sensor
The speed sensor in a car may experience issues due to moisture. A sensor may become faulty if moisture enters the sensor’s case. The sensor may also be impacted by condensation or precipitation from a humid environment.
9. Reduced Pressure In the Tires
Another potential reason for a speed sensor problem could be low tire pressure. To avoid sensor distortion when measuring vehicle movement, tires must be inflated. The sensors may not function at all if the tires are under-inflated because they will find it difficult to determine where the vehicle is moving.
10. Damage to the Speed Sensor
Damage to the sensor itself may result in a speed sensor malfunction. This may be the result of something striking or moving by the sensor, corrosion on the electrical connections, or both.
How is Bad Speed Sensor Symptoms Diagnosed?
It is crucial to take the time to diagnose your car once you start noticing the above-described signs of a bad speed sensor to determine whether the speed sensor is the issue.
The diagnosis can be made easier with a multimeter. This method will also be useful for those who are wondering how to test transmission speed sensors.
1. Park the Vehicle
Find a level, flat surface first, then park the car there. It will be simple to quickly access the speed sensor thanks to this plain surface.
Then, turn off the car and all other parts that are connected to the battery, like the lights. After that, you might want to take the key out of the ignition.
2. Find the Car’s Speed Sensor
Locate the wheel speed sensor close to the transmission by opening the hood of the car. Please locate the dipstick on the transmission and follow it to the metal sensor, which is attached to the transmission by two wires (black and white) and held in place by a metal bracket.
To be sure, check the owner’s manual for your specific vehicle as some speed sensor locations may be different from others.
The cruise control unit in the speedometer cable and vacuum valve by Hans Haase / CC BY-SA 4.0. The sensor’s inability to produce an accurate enough speed calculation prevents the operation of cruise control and anti-lock brakes.
3. Remove the Sensor By Unplugging the Wires
The wheel speed sensor can be removed by unplugging the black and white wires with a pair of pliers or screwdrivers. You can also use your fingers to unplug and take them out. To release the wheel speed sensor, locate a pull tab or button by the side or top of the sensor and press it.
Before removing the sensor, make sure to determine whether any screws or bolts need to be loosened. After that, carefully remove the sensor by wiggling or sliding it out of its position. Avoid attempting to force it out to prevent damage.
4. Connect the Speed Sensor Wires to The Multimeter
Connect the white lead to the red terminal while connecting the black lead to the black terminal. Then, gently insert the leads into the slots, making sure that they fit snugly. Then, by adjusting the dial, set the multimeter to AC, or alternating current.
5. Connect the Sensor to the Car
The sensor can be connected to the vehicle using a set of black and white wires. You can purchase this wire from an auto accessories store. The wire is made up of a black ground wire and a white signal output wire. Connect them to the sensor safely.
6. Connect the Black Lead to the Wire That Is Exposed
Establish a connection between the exposed wire and the black wire that is connected to the wheel speed sensor. The white wire connected to the sensor should then be connected to the red lead wire.
7. Test the Speed Sensor By Connecting a Drill Bit
Get a drill bit at this point, which will be used to mimic the movement of the sensor. To enable the wheel speed sensor to rotate the gear inside, find a drill bit that fits the sensor perfectly.
Connect the drill bit to a power drill and hold it securely but gently so it won’t fall off. Next, use the drill to rotate the speed sensor. Once it gets an accurate reading, speed up the spinning process after starting slowly.
8. Examine the Reading on the Multimeter
If the number in the multimeter increases in proportion to the speed when the speed sensor is being spun by the drill, the sensor is in good working order. The sensor, however, is flawed if it doesn’t speed up or fails to show any voltage.
It would be best to choose a replacement wheel speed sensor as soon as possible if yours is defective. Make sure to purchase the one that meets the requirements of your vehicle.
Guidelines When Removing the Speed Sensor
- The sensor can be taken out of its case by pushing a tiny button and pulling.
- You might need to gently shake it to get it out if it’s too tight. Don’t exert too much force, though, or you risk damaging it.
- Check to see if any screws need to be removed before removing the sensor.
- Attach the multimeter now. It is necessary to attach the black and red wires to terminals of the same color. When you hear a clicking noise, it will be connected.
The ABS light indicates a damaged speed sensor. The vehicle’s other electrical systems receive the speed sensor’s information about wheel rotation and pass it along to the engine control module.
Guidelines When Using a Multimeter
- Set the multimeter to measure the alternating current before using it.
- A slot is where the speed sensor is inserted. The sensor wires must be connected to the black and white wires.
- You must induce motion inside the speed sensor to test it. This can be done by using a drill bit. To connect, the drill bit must be the proper size.
- Once connected, the sensor can be moved. It should spin as quickly as it can before you get a reliable reading.
- Start slowly and increase your speed gradually. Once the speed is increased, take another note of the reading.
- The reading ought to increase as the speed does.
- A speed sensor symptom is present if the reading does not rise with speed.
- Replace the sensor as soon as you’ve identified the issue.
- Before you replace it with a new one, make sure it has the same specifications.
- Test the new sensor after installation to make sure it is functional.
You will find it simple to recognize speed sensor symptoms if you follow the steps mentioned above. By checking the sensor on your own, you can save money. If it is flawed, you can then replace it with a new one.
To complete the work on your own, you will need the tools listed in the following section.
How Much Does a Bad Speed Sensor Replacement Cost?
A bad speed sensor can be replaced for between $125 and $265. While the labor price to fix the component ranges from $69 to $87, depending on the circumstance. However, the price of the part varies depending on the location or auto part dealer.
The make and model of the vehicle will also influence the overall cost of replacement because some may be more expensive than others. Therefore, be sure to find out how much a wheel speed sensor replacement for your car’s make and model will cost in your area.
Is It Safe to Drive with Bad Speed Sensor Symptoms?
Driving without a speed sensor or with one that is malfunctioning can be very dangerous. The function of the speed sensor is crucial to the safety of a driver. The sensor assists in calculating the vehicle’s speed so that the driver can determine when to apply the brakes.
Therefore, while driving, a malfunctioning speed sensor prevents the computer from calculating the required speed level to increase engine power or apply the brakes. A malfunction in the safety system could result in a fatal accident.
If you’re unsure of how long you can operate a vehicle without a speed sensor, read on. This is not something to think about. If you discover that the speed sensor in your car needs to be replaced, doing so right away is recommended.
Do Speed Sensors Fail Often?
You cannot predict how long your wheel speed sensor will last using strict rules. It depends on the vehicle you drive and how you take care of it. The sensors are affected by outside factors. However, the speed sensors typically last for 50,000 miles.
Low tire pressure is yet another probable cause of a speed sensor issue. Tires must be inflated to prevent sensor distortion while sensing vehicle movement.
Can Bad Speed Sensor Symptoms Lead to Limp Mode?
Yes, a faulty wheel speed sensor can put a car in limp mode. Stability and traction control may be lost as a result of a defective wheel speed sensor. The traction control and stability systems may then be turned off by the ABS as a result of this.
In limp mode, this persistent malfunctioning may occur. Limp mode, which hibernates some of the crucial parts of the car, is activated when a car’s computerized systems detect a critical engine or transmission fault automatically.
Therefore, because it is a crucial sensor among the parts of the car, when a wheel speed sensor malfunctions, the car may enter limp mode.
Can Bad Speed Sensor Symptoms Lead to Rough Idle?
The computerized systems of a vehicle will receive incorrect signals from a malfunctioning speed sensor, which will impair the operation of other car systems.
As a result, those who wonder whether a bad speed sensor can cause rough idle. An unreliable speed sensor will result in a rough idle and extra fuel consumption.
Other engine problems like reduced acceleration and other problems can also be brought on by incorrect signals being sent from the speed sensor area to the vehicle’s fuel system.
Therefore, if you find that the wheel speed sensor in your car needs to be replaced, do so right away because the consequences could be unpleasant.
Can Bad Speed Sensor Symptoms Lead to a Less Powerful Engine?
Yes, because the wheel speed sensor is so delicate, a malfunction could result in diminished engine power.
Additionally, the sensor is made to improve shifting while the engine is running. The sensor’s inability to communicate with the car’s computer system will prevent it from controlling the engine’s rev limiter when it develops a fault.
Because the systems are interconnected, when this occurs the car will not only enter limp mode but also turn off the reduced engine power light.
If the question “Can a bad speed sensor cause stalling?” is also on your mind. Even though it may not be a direct result, the impact of a bad speed sensor can still cause the engine to stall.
Can Bad Speed Sensor Symptoms Lead to Braking Problems?
Of course, brake problems could result from a bad wheel speed sensor. However, the standard brake system in the car is typically unaffected by the issue. The anti-lock brakes are frequently impacted by the issue.
An automobile’s anti-lock brakes will be impacted and become dysfunctional by a faulty wheel speed sensor. As soon as this happens, the ABS warning light will turn on and appear on the dashboard of the vehicle.
Can a Bad Speed Sensor Produce Weird Noise?
A damaged wheel speed sensor can have an impact on various parts of the car and manifest symptoms in various ways. A bad speed sensor may cause symptoms like the ABS warning light to come on, traction control issues, etc. in addition to noises coming from the wheels of the vehicle.
A torque converter by BerndB~commonswiki / CC BY-SA 3.0. The transmission torque converter’s failure to engage the clutch and establish a mechanical connection between the engine and the gearbox is one of the most prevalent problems with speed sensors.
If you notice any of the signs of a bad wheel speed sensor, make sure to fix it as soon as you can. An issue should be resolved as soon as possible rather than waiting until it becomes more difficult.
After some time behind the wheel, you might start to experience the symptoms described in this article for the speed sensor. It’s crucial to comprehend every sign of a bad speed sensor so you can act quickly to fix the issue.
You might have a problem if the speed sensor in your car starts to emit a check engine light or if the speedometer stops working. Any of the aforementioned symptoms should be checked out as soon as you notice them. Quick action will guarantee that your car doesn’t sustain more severe damage.
Driving while your speed sensor is broken could be very risky. It might result in an accident and significant damage to your car. If you experience any speed sensor symptoms, you need to get it fixed right away.
You wouldn’t want to wait until something goes wrong to try and determine what caused it, would you? To identify the problem and then fix it, follow the instructions in this article.
Jim Wicks is the founder of MotorVehicleHQ. With over two decades of experience in the automotive industry and a degree in Automotive Technology, Jim is a certified car expert who has worked in various roles ranging from a mechanic, car dealership manager, to a racing car driver. He has owned more than 20 cars over the past 15 years. Ask him about any vehicle you see on the road and he can tell you the make, model and year. He loves the aesthetics of all things cars, and keeps his vehicles in pristine condition.
In his free time, Jim enjoys getting his hands dirty under the hood of a classic car or taking long drives along the country roads. His favorite car? A 1967 Shelby GT500, a true classic that, according to Jim, “represents the pure essence of American muscle.”