There are two types of speed sensors available for a vehicle. There is the engine speed sensor and the transmission speed sensor.
The engine speed sensor detects how many revolutions per minute (RPM) your engine’s crankshaft is spinning in real time. The transmission speed sensor detects how fast your car is traveling on the road.
When you look at your dashboard, you can see the tachometer representing the engine speed and the speedometer representing the transmission speed. Both sensors are constantly communicating with the engine control unit of the vehicle.
The information the engine control unit receives from these sensors will allow it to take the appropriate actions with the functioning of the engine and transmission. All the sensors are equally important and have an indirect impact on other components of the vehicle.
Faulty Speed Sensor Symptoms
The transmission speed sensors are built into the wheel hubs of your vehicle. This is how the speed and movement of the vehicle get calculated by these sensors. However, the transmission of your vehicle depends on both types of speed sensors in order to function properly.
If either or both sensors were to malfunction, then you would experience a wide variety of symptoms from your vehicle. These are not symptoms that you could tolerate for very long because they will gravely impact your ability to drive safely.
Below are the top 4 symptoms of a faulty speed sensor that you should watch for.
1) Malfunctioning Cruise Control
The transmission speed sensors need to be functional if your cruise control mechanism is going to work properly. If the engine control unit cannot receive the proper information about the vehicle speed, then your cruise control will never be able to maintain the same speed.
The engine control unit will be able to detect this problem, so it automatically prevents cruise control from being used until the problem is fixed. If you do not normally use cruise control but you expect your speed sensors are faulty, test them out by attempting to use cruise control and see what happens.
2) Check Engine Light
When the “Check Engine” light illuminates, this could mean almost anything. But if you have malfunctioning cruise control and a Check Engine light coming on, this is a clear indication of a faulty speed sensor.
After all, the engine control unit depends on having valid speed information regarding the engine’s crankshaft. If it does not receive this accurate information, it will signal to the driver by automatically illuminating the “Check Engine” light.
3) Long Shifting Intervals
The engine control unit communicates with the transmission. If the transmission speed sensors end up failing, the unit won’t be able to properly manage the gear shifting actions that you make.
As a result, you may notice the timing of your shifting will be off. This means there will be a small waiting period between each shift that you make.
4) Difficulty Shifting
Along with the shifting intervals that you will experience, shifting the stick will be more difficult in general. You may notice the stick shift either feeling rougher as you try to change gears, or it will feel too fast.
In order to be a safe driver, the shifting experience needs to be smooth. It should not be too hard or too easy.
Read also: Coolant temperature sensor problem symptoms
Speed Sensor Replacement Cost
The replacement cost of the average speed sensor will be between $20 and $50. Sometimes there are speed sensors as cheap as $8 while others go up to $100. Then you need to consider the labor costs on top of that which is another $50.
Although this is not much money, they can add up if you have multiple speed sensors go bad.