Why You Need to Change Speed Sensor in Car

Every car needs a speed sensor to keep track of the speed you’re driving at. If your sensor isn’t functioning correctly, your car won’t be able to calculate your speed accurately and could lead to dangerous consequences. Learn how to change a speed sensor in a car in this article.

Why is my car slowing down?

One of the most common problems drivers encounter is their car slowing down. This could be attributed to a number of reasons, but one of the most common ones is a faulty speed sensor.

Signs that your speed sensor needs to be replaced

Your car’s speed sensor detects how fast you’re driving and provides data to the electronic control unit (ECU). If it’s not working properly, your car may not go as fast as you think it does, or worse yet, it may suddenly and unexpectedly speed up. If you suspect your speed sensor needs to be replaced, here are some signs that say so.

1. Your car’s speedometer doesn’t seem to be accurate.
2. You notice unexpected increases in your car’s speed when you don’t press on the gas pedal as much as you used to.
3. The car suddenly and unexpectedly starts going faster than usual when you take off from a stoplight or when starting from a dead stop.
4. You see warning lights or a “Service Engine Soon Warning” message on your car’s dashboard indicating that your speed sensor is about to go out.

How to replace a speed sensor in a car

The purpose of a car speed sensor is to measure the speed of the car and send this information to the car’s Electronic Control Module (ECM), which uses this data to control various functions in the car, such as the ignition timing and fuel injection. If the speed sensor is malfunctioning, it may not be sending accurate information to the ECM and this could lead to problems with the car’s performance.

There are a few things you need before you start replacing a speed sensor in your car:

1) A diagnostic scanner that can read and clear trouble codes from your car’s ECM. This is optional but recommended because it can help you identify if there is a problem with the sensor.

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2) A set of multimeter probes or a tachometer so that you can measure the engine speed while you are working on the car.

3) The correct tool for removing the old sensor: a 10 mm socket, wrench, and ratchet.

4) Ethanol or gasoline cleaning fluid (to clean any dirt or debris that has built up on the sensors over time).

5) The new speed sensor.

Checklist for repairing or replacing a speed sensor in a car

1. Have the car serviced?
If your car is not currently in the shop, it may be time for a speed sensor replacement or repair. A clogged or faulty speed sensor can cause your car to hesitate and slow down, which is especially dangerous when driving in stop-and-go traffic.

2. Is the sensor physically damaged?
If you’ve noticed that your car’s acceleration seems slower than usual, it might be time to check the speed sensor. Depending on how severe the problem is, you might need to replace the unit altogether. In some cases, a broken or dislocated sensor can just need a quick fix with some pliers; other times, you may need to take your car in for repairs.

3. Does the sensor appear to be working correctly?
If there’s any question as to whether or not the sensor is actually causing the issue, you should test it by replacing it and seeing if the problem goes away. Once you have a reliable method of confirming that the sensor is either malfunctioning or broken, it’s time to take action.


If you have a car that uses a speed sensor, it is time to change it. The average life of the speed sensor on a car is around 10 years, but after that point the device will start to incorrectly calculate your driving speeds and may even cause the car to stop in traffic or worse. If you’re not sure if your vehicle has a speed sensor, you can check by looking for an orange or black wire coming out of the engine compartment near the transmission. If your vehicle does have a speed sensor, changing it is definitely worth it for improved safety and efficiency on the road.

DynoCar is the best place to find information on all things cars, whether it be a car buying guide or how to change your oil. We’ve made finding and staying in touch with car information easy and fast.



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