Although bad speed sensors can’t stop your car from running, it is not advisable to drive with them as you could be jeopardizing your safety.
Speed sensors are usually attached to wheels to detect the speed at which they move, as well as the rotational speed of the wheel to which they are attached. Just like a four-wheeled car would have four-wheel sensors, every other car would have a proportional number of speed sensors for the number of wheels.
They are otherwise called wheel speed sensors, ABS sensors or transmission sensors and they act as the ‘middleman’ between the wheels and the control unit.
By implication, they help in transmitting information to the system in the form of electrical signals. When the wrong signal is sent, it affects the functionality of the car adversely. This is what happens when you drive a car whose speed sensors have gone bad.
Detecting bad speed sensors is much easier than you think. Apart from the fact that the ‘check engine’ indicator light would be turned on, there are other noticeable pointers that will give the state of the sensors away.
In a situation like this, it could be difficult to know the exact speed sensor with the problem, hence it will be advisable to troubleshoot to know the affected one. The beautiful part of it is that speed sensors are inexpensive to replace and it would be in your best interest to replace them all at once.
Causes of Failed Speed Sensors
Bad speed sensors do not just happen overnight, neither does it happen magically. Imagine buying a new car with bad speed sensors. That is impossible. How then do we end up with bad car speed sensors? What are the major causes? Can it be possible to guard against the occurrence at all?
Find below three causes of failed speed sensors.
When the car is not properly maintained, it tells on the parts including the essential parts upon which the vehicle’s functionality lies.
The magnetism of a speed sensor, for example, would reduce if the surface is covered in grime. When this happens, speed sensor misbehaviors are inevitable.
Adopting a good vehicle maintenance practice would not only keep your sensors safe but would also protect other vital parts from damage and keep the vehicle running at its best.
Due to prolonged usage and harsh driving conditions, car sensors can get damaged. This is because every mechanical device is prone to wear and tear.
Speed sensors have both plastic and magnetic parts. While the magnetic part could wear out and lose its magnetism, the plastic part could also suffer breakages due to pressure.
The speed sensor could also develop an internal fault, thereby making it impossible to relay accurate information.
When a speed sensor is damaged internally, it tells on the signal being emitted and the information being relayed.
While the fault could result in the sensor giving off no signal at all, it could also give incoherent signals which could lead to difficulty in interpreting the message being portrayed.
5 Bad Speed Sensor Symptoms
Since the vehicle is directly dependent on the information being conveyed by the transmission sensor, any wrong transmission directly affects the performance of the engine.
The effects of this can be vividly seen through the following signs:
Inconsistent Speedometer Readings
The speedometer and speed sensor work hand in glove. While the speed sensors detect the moving speeds of car wheels, a speedometer indicates the speed of the vehicle and relays it to us in a language we can understand.
Therefore, it is safe to say that the speedometer is dependent on the speed sensors to carry out its duty. When your speed sensors are malfunctioning, the speedometer could start giving inconsistent readings or no reading at all. This may render every driving session unsafe as you will never be sure of the speed at which you are driving.
You may be a careful driver but having a speedometer to monitor your pace is still necessary.
Loss of Traction
When the speed sensors in your car are damaged, it will tell on your ability to maintain a constant driving speed.
The frictional power of your car would also reduce and you will find it very difficult to control the wheel properly. The car does not just run based on your driving skills alone. The information received by the system from the transmission sensor is equally important to keep your car balanced on the road.
A faulty speed sensor means an invitation to danger.
Check Engine Indicator Light
The “check engine” light on the dashboard works for several engine parts. If this light happens to be switched on at any point in time, it signifies that something is wrong with one or more parts of the engine, one of which could be the speed sensor.
To confirm this, an OBD-II scan tool would be needed to scan the engine and detect the affected part. More often than not, we pay little or no attention at all to the indicator lights present on the dashboard, except the fuel gauge light, of course. This is a habit that needs to be checked as paying attention to the indicator lights could go a long way in saving time, energy and cost.
In this case, cars with automatic transmission suffer more than manually operated cars. Since the car is automatic, it implies that it is dependent on the transmission from the wheels.
Any problem with the speed sensors, no matter how little directly affects the wheels and this, in turn, has a negative impact on driving.
Poor transmissions from the wheels could result in instability, irregular gear changes, loss of control, delayed shifts amongst others.
How to Identify a Bad Speed Sensor
Since each of the wheels of the car’s wheels has its speed sensor attached to it, it may be difficult to distinguish the bad from the good. However, with the aid of a sensor scanner such as an OBD-II scanner, this can be achieved.
The first line of action should be to thoroughly access all the wheel speed sensors to ensure that they are not physically damaged. Once you are sure of your result, subject each sensor to a troubleshooting process to detect the faulty one. This is done when the vehicle is in its resting position, that is, it is not moving.
The scanner should be connected to your car and boot to detect your car’s Vehicle Identification Number (VIN). The control unit should then be enabled and information about the car’s anti-brake system loaded. Next comes the scanning phase after which error codes from the vehicle are found and displayed.
By clicking on wheel speed sensors, the faulty speed sensor can be detected here. Do not forget that the car is not moving, thus, wheel speed sensors should read zero.
If you happen to find a wheel speed sensor that is not reading zero, it has to be the faulty one. The implication of this is that any reading greater or less than zero is that of the faulty wheel speed sensor. This has to be taken out and replaced as soon as possible.
A very good example of the OBD-II scanner is the Autel MaxiCOM MK808. Other anti-brake system scanners can also be used, as long as they are compatible with your car.
Failed Clutch Application
In every car, be it manual or automatic, there is a strong connection between the clutch, the brakes and the gear system. Unfortunately, the gear system is also heavily impacted upon by the speed sensors. This makes them interdependent on one another and a problem with one could simultaneously affect the other.
If any wrong message is relayed by the speed sensors, this could have an adverse effect on the clutches as you would not be able to apply them. This means an inability to change or put the car in the correct gear, especially in manually operated cars and difficulty in applying the brakes.
The result is quite evident: slips, leaps and overheated transmissions.
The question of how long you can drive your car with bad speed sensors should not arise at all.
Even though an irregularity in the speed sensor would not stop you from driving your car over long or short distances, attempting to drive such a car means putting yourself and every other passenger at risk of road accidents.
It is also important to note that speed sensors can only be replaced but cannot be repaired. Once a speed sensor is damaged, it is rendered completely useless. In this case, there is no temporary arrangement and an immediate replacement of the faulty ones is the only solution.