How to Fix a Speedometer

If you need to replace your car’s vehicle speed sensor, it’s possible you could expect the repair to cost between $150 and $400.
Written by Melanie Krieps Mergen
Reviewed by Melanie Reiff
How to fix a car’s speedometer depends on the cause of the problem and what type of speedometer it is. If you need to replace your car’s vehicle speed sensor, it’s possible you could expect the repair to cost between $150 and $400.
Speedometers have been a standard vehicle component since the 1910s. This makes it pretty easy to take a car’s speedometer for granted—that is until it stops working. Without a working speedometer, it’s nearly impossible to tell whether you’re driving at a safe speed and an improper reading could be the reason you end up with an unexpected speeding ticket.
That’s why it’s helpful to know how a speedometer works—and what you can do when it stops responding. Courtesy of
, the
trusted insurance comparison app
that helps drivers save time and money on
car insurance
shopping, here’s what you should know about your car’s speedometer.

What is a speedometer, and what does it do?

If you’re going to be fixing a problem with your speedometer, it helps to know what it does. Simply put, a speedometer is a gauge on your instrument cluster that measures a vehicle’s speed.
You’ll find your speedometer on your instrument cluster amid other gauges, like your tachometer or RPM gauge, the oil pressure gauge, and your fuel gauge.
MORE: Speedometer sensor replacement
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How does a speedometer work?

How a speedometer works depends on what type it is. 
Speedometers can generally be broken up into two different categories: electronic speedometers and mechanical speedometers, also referred to as cable-driven speedometers. Here’s a breakdown of how each one functions.

Cable-driven speedometer

Just like it might sound, a cable-driven or mechanical speedometer measures the speed with the help of a speedometer cable attached to a vehicle’s transmission. 
Getting a speed reading from a cable-driven speedometer is a chain reaction of events.
As you’re driving down the road, the speedometer cable will start spinning. A magnet attached to the cable will start to spin as well, creating a magnetic field that causes a metal component known as the speed cup to move, and this movement in turn will cause the speedometer needle on your instrument cluster to move, which will give you your vehicle’s speed reading.

Electronic speedometer

An electronic speedometer doesn’t get its speed information from a drive cable. Instead, it uses a vehicle speed sensor (VSS). 
A good number of modern vehicles use electronic speedometers. The vehicle’s VSS is attached to the driveshaft. As it rotates, one or more sensors attached to the driveshaft will pass the sensor, creating an electric current. The sensor uses the timing of that pulse to calculate your vehicle speed.
MORE: How long does a speeding ticket stay on your record?

Why is your speedometer not working?

There are a number of culprits that could cause a speedometer to stop working. Regardless of the cause, though, it’s a problem you should fix as soon as possible. 
The first step in finding a fix for your speedometer is finding out why it’s not working. The following are just a few examples of common causes of a faulty speedometer.

Bad speed sensor or speedometer cable

On a mechanical speedometer, a worn cable could lose its ability to spin the way that it needs to, interrupting the chain reaction process that gives you your speedometer reading.
On an electronic speedometer, a faulty speed sensor could prevent it from working properly. If the VSS isn’t working, your vehicle doesn’t have a way to measure how fast the driveshaft is spinning to calculate your speed. Because it can’t determine vehicle speed, this can also prevent your cruise control from functioning.

Electrical or computer problems

If you have an electronic speedometer, it’s possible you may have a larger problem with bad wires or connectors, your instrument cluster, or the engine control module (ECM) or engine control unit (ECU) rather than your VSS or speedometer cable. This could especially be the case if you notice you have problems with multiple gauges on your instrument cluster and not just your speedometer.
Whether it’s a sensor problem or another electrical problem, the ECU may detect this and trigger the
check engine light
to turn on in response.

Improper tire size

If your current tires aren’t the standard size for your vehicle, it’s possible it could be causing you to get inaccurate speedometer readings. Your vehicle’s tire size plays a significant role in the calibration of the speedometer and how it determines your speed. If you introduce new tires with a different circumference into the mix, suddenly, the calculations used to calculate your vehicle’s speed have been thrown off.
This could affect the accuracy of your odometer, too, which tracks how many miles you’ve driven.

How to fix a broken speedometer

The approach to fixing a malfunctioning speedometer will depend on what’s causing it. That could look like replacing a faulty speed sensor or speedometer cable, or fixing wiring or other electrical components that are a part of the ECM. 
Having a mechanic inspect your speedometer and other vehicle components can help you find the source of your speedometer’s problem and how it can be fixed.

Can you drive with a broken speedometer?

While you could technically still drive a vehicle with a broken speedometer, it isn’t a good idea. Speed limits are in place for a reason, after all. 
Without a speedometer, you won’t be able to tell whether you’re driving at a safe speed in a particular area, and that can be dangerous for you, other drivers, and pedestrians. You’re also at a higher risk of getting a speeding ticket (which could also raise your car insurance rates).

How much does speedometer repair cost?

How much it costs to repair a speedometer depends on its problem. For a good number of potential speedometer repairs, like replacing a vehicle speed sensor or speedometer cable, costs at the repair shop can potentially range from $150 to $400 for parts and labor, but this can vary based on the particulars of your own speedometer’s problems.

Find affordable car insurance

Being able to see your car’s accurate speed is obviously important—but so is having a good read on your
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How you should go about fixing a speedometer gauge depends on what’s wrong with it. A mechanic can inspect a speedometer’s components, run electrical diagnostic tests, and perform some troubleshooting to try and find the source of the problem, then determine the right solution for you.
Many auto parts stores sell new speedometers. If you’re looking for an OEM speedometer, you may want to contact a dealership for your vehicle manufacturer to find out the best way to purchase and install a new speedometer.
Your speedometer might be broken if it gives you no reading, readings that are clearly inaccurate, or speed readings that fluctuate rapidly or inconsistently.
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