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Speed Sensor Problems – Here’s What You Need To Know

Why You Should Keep Your Speed Sensors On Check

The speed sensor is a crucial component of your internal transmission system in your vehicle. The speed sensor, also known as the vehicle speed sensor or VSS, measures the transmission output. This data relates directly to the vehicle speed and how fast you are moving. This information is being transferred to alter the engine functions like air and fuel ratio, shifting times, and diagnostic fixes. 

Auto Repairs Are EXPENSIVE

Speed Sensor Symptoms


There are common symptoms that are typically attributed to a faulty engine speed sensor. By figuring out these symptoms before they get any worse, you can prevent further damage to your internal engine system, leading to a reduction in engine repair cost and the need to replace your engine eventually. Keep in mind that an engine replacement is one of the most expensive processes you can have in your vehicle, so preventing this from occurring will keep your car running for a much longer period of time.


A faulty vehicle speed sensor can cause other issues besides just the engine performance. Symptoms of faulty speed sensors can result in a damaged battery coil pack, faulty throttle position sensor, and other sensor issues, resulting in a lack of communication between parts. The most common speed sensor problems are as follows.\


  • Transmission revving


If your transmission revs excessively when you are shifting, this is a classic speed sensor problem. Make sure you keep an eye and ear out for the most common transmission issues to prevent these from shutting down your car completely. 


One of the other most common transmission problems includes gear slippage. If your transmission slips out of gear or shifts at incorrect times, this is a clear sign of a failing transmission and one of the main speed sensor problems. Along with the revving, while shifting, gear slippage can make your car unsafe to drive.


Another sign of transmission issues that directly result from speed sensor problems includes hesitation while shifting gears. If you go to shift and your car does not respond right away and takes longer to respond appropriately, then your transmission is in trouble. The car hesitating while shifting goes hand in hand with a higher RPM while revving your car, which is both common results of speed sensor problems.


  • Long Shift Intervals


If you find that the transmission speed sensors fail and are having speed sensor problems, you are going to have a more difficult time changing the gear at the correct time and maintaining that gear choice. Due to the speed sensor problems, each shift’s timing will be off, meaning that there is an excessive waiting period between shifts, leading to a jerky and uncomfortable ride. 


  • Check Engine Light


When the check engine light illuminates on your dashboard, it can be due to multiple reasons. Some of these reasons are quite severe, and some of these reasons are pretty minor that can be taken care of in just a few minutes or a quick trip to the mechanic. However, your speed sensor problems can trigger the light to come on and a warranted check-up at your auto body shop.


The engine control unit, which is the car’s internal computer in charge of making decisions, depends on having the correct data and speed information regarding the engine’s crankshaft timing. If the information that is sent to the engine control unit is not correct or is sent at the wrong time, it will tell the driver that there is an issue in the vehicle by turning on the check engine light on the dashboard. 


  • Malfunctioning Cruise Control


The transmission speed sensors need to be working correctly and at the optimal level if your cruise control is going to work and keep your car at an even speed while driving down a road. If the engine control unit does not get the right data about your car’s speed, your cruise control will not be able to maintain the desired speed set by the driver. 


The engine control unit will then detect this issue and a mechanic fixes malfunctioning sensors in your vehicle to prevent the cruise control from being used until the speed sensor problems. If you do not usually use cruise control in your car but have a feeling that the speed sensor problems are causing issues in your vehicle, try to test them by turning on your cruise control to see if it works as it should. 


  • Rough Gear Changes


Along with the car’s transmission revving at a very high RPM when shifting and gear shifting timing being off, rough gear changes also indicate speed sensor problems that can harm your transmission. This is actually one of your car’s most common speed sensor symptoms since the gear shifting will be rough and unsmooth, leading to an uncomfortable ride for all people in the car. 


  • Speedometer Malfunction


Along with the problems with the cruise control and check engine light, another problem in your vehicle’s dashboard directly relates to the speedometer. If the vehicle's speedometer all of a sudden stops displaying the speed or is no longer accurate in the speed it is displaying, and this is a clear sign that you have speed sensor problems. 


This is a very dangerous situation since you will no longer know how fast you are driving. Not only will this put other cars and yourself at risk, but you are in serious jeopardy of getting an expensive ticket from a police officer. 


  • Overdrive Light Blinking


The overdrive light on your dashboard can indicate a problem depending on various other conditions in the car. The light mainly indicates two separate problems depending on whether the light is blinking or constantly lit up while driving. 


If the overdrive light comes on and stays on during use, this just means that your car is not using an overdrive, and you have nothing to worry about. The overdrive process means that your car is ready to maintain a steady speed while you are driving and reduces engine speed to save energy.


Using overdrive in your car saves fuel economy and heightens fuel efficiency, resulting in less stress on your car and better gas mileage. Having the overdrive can help increase your gas mileage while you are driving consistently on the highway over long distances. 


However, your overdrive light will mean something completely different if it is flashing or blinking. In this case, it will not be quite a simple fix as if the light has remained on. This means that there is something wrong with the transmission in your car, or perhaps indicates speed sensor problems. 

Transmission sensors

There are various transmission sensors in your car, all with different functions and purposes. All of these sensors work together to read, analyze, and use data to determine the next move. Transmission sensors work together to keep the transmission working correctly, reduce any problems, and prevent any future problems – especially speed sensor problems. 


These sensors work as a team to help your transmission function correctly. The transmission function is transferring the power from the engine to the driveshaft and the rear wheels or the axle half-shafts. The gears inside the transmission change according to the car’s speed and change the torque based on the engine’s speed and current torque. 


In order to know if the bad sensor can cause transmission problems, then you need to know the different types of transmission control module sensors in your vehicle. Knowing the various sensors within the transmission shows how they relate to the speed sensor problems that can arise in your car. 


  • Throttle position sensor



One of the sensors that send signals to the transmission control module is the throttle position sensor. This sensor provides a data source, with the information coming directly from the vehicle’s throttle position. If the throttle sensor cannot send the proper location, then the throttle position sensor tells you that the transmission control module is faulty. 


The throttle position sensor signal alerts the module as to how much load is placed on the engine at one time. This information can help the transmission control module figure out if the car’s position requires it to upshift or downshift at a specific time. The TCM can also analyze this data, and then compare this information to the vehicle sensor speed data to figure out which shift is most appropriate. If your vehicle is having trouble shifting, this is a sign of a faulty TCM or speed sensor problems. 


  • Vehicle speed sensor 



The transmission control module uses the vehicle speed sensor to determine how fast the car is traveling, so it knows when to change gears. If this sensor is not functioning correctly, the transmission control module can choose the wrong gear at the appropriate time, causing the transmission to slip. This is how you know if your transmission control module is bad and can help you fix any future speed sensor problems. 


  • Wheel speed sensor



The wheel speed sensor data helps the transmission control module know what the car is currently doing. Basically, this means that the wheel speed sensor tells the transmission control module what is happening in the car. The wheel speed sensor lets TCM adjust the shifting and gear changing. The wheel speed sensor also notifies the TPM of when to control and alter the torque converter’s function, preventing any speed sensor problems.


  • Turbine speed sensor



The turbine speed sensor, also known as the input speed sensor, is in charge of telling the TCM certain details. The transmission control module uses this data to determine the slippage amount to put on clutches, bands, and the torque converter clutch. Without this ability, the transmission control module will not apply the proper tension, leading to imminent speed sensor problems. 


  • Engine Control Unit



The engine control unit is the brain and working computer of your vehicle. This component, along with the transmission control module, works to make the vehicle operate efficiently. Some of the ECU functions are in charge of including turning on the check engine light, storing error codes that can help you diagnose any speed sensor problems, and changing the engine’s RPM to account for any gear change. 


Since the transmission control module is electrical with circuit boards and wiring, it holds different shifting programs. These codes allow the transmission control module to analyze the sensors’ data versus the preset parameters for your specific vehicle. 


Once the codes have been set, and the parameters are made, the engine control unit adjusts the shift times based on the solenoids to fit the driving situation. If the ECU and the TCM are not working, this can lead to future speed sensor problems.  


  • The Manual Lever Position Switch


The Manual Lever Position Switch, also called the Transmission Range sensor, has a very important vehicle function. The job of this switch is to tell the PCM the location of the transmission shifter. The PCM will use this data to control which one of the transmission gears has to disable or enable. 

During the failure of this sensor, your car can enter into the wrong gear starts. Additionally, there will be no upshifts, either. If you feel the performance is off and this position switch is not working accordingly, you might also notice the vehicle’s subsequent speed sensor problems. 

Speed Sensor Replacement Cost

Although this sensor is not the most expensive repair or replacement in your car, the cost to replace a transmission sensor can add up over a prolonged period of time of owning a vehicle. However, this is key to preventing any speed sensor problems that can lead to future issues within your more expensive vehicle. 

The average cost for a transmission position sensor repair or replacement can run you about $240 all the way up to $350. While our estimates are the average, you have to factor in the high labor costs as well. Those costs can cost you anywhere between $125 and $160.



You might be wondering to yourself, “how can I avoid any speed sensor problems in the future?” One of the ways to avoid having any issues with your transmission and speed sensors is to keep an eye out for the most common speed sensor symptoms and be ready to pay the necessary replacement cost!  

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