3 Symptoms of a Bad Speed Sensor (Engine or Vehicle Speed)

Last Updated on September 10, 2020

There are two common types of vehicle speed sensors and they each play a different role. One type (engine speed sensor) is usually installed on the transmission or transaxle, and the other type (vehicle speed sensor) is installed on the knuckle arm on the four wheels.

Looking for a good online repair manual?
Click Here
for the 5 best options.

The engine speed sensor takes data from crankshaft position sensor that give information for the engine spin speed. Vehicle speed data comes from the speed sensor which is located on the wheels and sends information regarding wheel spin speed.

Therefore, any fault from either speed sensor or any symptoms showing how defective it has become can lead to a wide range of abnormal problems in your vehicle if you fail to pay attention to it in time.

Common Bad Speed Sensor Symptoms

#1 – Rough Gear Changes

incorrect transmission shifting

One of the most common speed sensor symptoms of your car is that the transmission will not smoothly change gears of your vehicle because of higher transmission revs. This means that the car engine runs at higher speeds than the car itself.

You may also find it very rough while shifting gears and as the problem worsens, you will find it unbearable to change the car into higher gears. This means that the vehicle’s transmission will eventually engage into overdrive very late.

Why Does This Happen?

The transmission of your vehicle can only shift smoothly with the help of a healthy speed sensor. This sensor counts the number of internal revolutions in the transmission. Consequently, the control unit of the transmission receives the data then makes the necessary adjustments after calculating the rotational speed.

Unfortunately, it is impossible to repair the transmission speed sensor as it simply fails. You have to discard it and replace it with a new one. A professional mechanic should help you examine and diagnose the speed sensor system of your vehicle even though the symptoms may seem similar in all cars.

#2 – Speedometer Malfunction

speedometer not working

Once the vehicle’s speedometer stops functioning all of a sudden, this is a sure fire sign that indicates the speed sensor has become defective. The malfunctioning speed sensor means that the speedometer will not have the ability to read the speed of your car.

This is very risky because you will drive without knowing the exact speed that your car has registered. This can land you in trouble with the authorities or even cause unnecessary and avoidable accidents.

#3 – Check Engine Light On

check engine light

Furthermore, sometimes the check engine light may light up recurrently and periodically as you accelerate without any good reason.

To understand what the check engine light means, you should use diagnostic tool or car OBD scanner to get the trouble code(s) which will help troubleshoot the issue. For example, DTC P0500 (Vehicle Speed Sensor Fault Conditions) may appear to confirm the issue.


Many problems can arise if your vehicle has a faulty speed sensor. Indeed, a car that shows the symptoms of a worn-out speed sensor can bring about other related symptoms to other parts of the car, such as a faulty throttle position sensor or even a malfunctioning coil pack.

Faulty speed sensor symptoms come with some common characteristics that can affect your car engine and its related components.

And finally, any of the above speed sensor symptoms should prompt you to take your vehicle to an auto repair shop or trustworthy mechanic so that they can run a computer diagnostic on your car to identify the faults.

Even though some of the above symptoms may point towards a malfunctioning transmission, it is advisable to visit a repair shop having the best computer diagnostic equipment even before visiting a repair shop specializing on speed sensors to ascertain the real problems.



  1. I have a 2000 dodge neon and when you have it started and your foot on the patel and take it off it shunts off and the rpm gauges dont work i need help.

  2. I have a 91 ford f150 automatic it will run good then it will get where it will not pull park it for 2 days and it will run good again

  3. i have a 2004 mercedez c240. My gear will not change even after a long drive i have changed my faulty speed sensors but the problem still remains. do i also change the back axle shaft.

  4. I have a 2007 Toyota Camry. I had to have a Jump start yesterday and when I got it, I went to go take off in my car and it wouldnt move. My foot was on accelerator and the rpm would only got 5o 2 and the idle only would go ton15 mph by itself. Accelerator wouldnt work. I changed battery and checked all fuses. And I tried to reset it like I was showed on you tube. Still nothing what could be wrong

    • It shouldn’t damage the speed sensor but towing a rear-wheel drive vehicle backwards is just asking for trouble since the front wheels are made for turning. It could fishtail or you could break the steering linkage. The correct way would be to disconnect the driveshaft and tow with the front wheels on a dolly or simply use a flatbed trailer.

  5. We have a 2006 Nissan titan 2 wheel drive we’ve fixed the speed sensor inside of transmission and one on the side which i think is the output sensor and it’s still acting up. Once on the hwy when we hit 60 mph it sounds kind of loud and when barley taking off we feel a grinding noise and it’s burning oil from the engine like crazy do u know if there’s another sensor?

    • Check whether there is any cables broken near the wheel base. It usually happens when the un-professional mechanics doing these kinds of jobs., They wont care about the cables or sensor parts installed on it. By pushing forcefully removing the wheel base for brake pads its cause to breaks. Its my personal experience. I did myself to trace the cables and joined with connectors. Problem solved.


Leave a Comment