Why Speedometer and Odometer Not Working?


When driving a vehicle, it’s crucial to know how fast you’re going and how far you’ve traveled, so if the speedometer and odometer aren’t working in your car, they need to get fixed and fast. However, if you’re not a mechanic, it can be difficult to determine why these functions aren’t working as they should. 

Your speedometer and odometer are not working, due to a broken Engine Control Unit, a blown fuse, or a malfunctioning speed sensor. Analog odometers might not be working due to a broken gear or another component.

If your speedometer isn’t working, there’s a good chance your odometer also isn’t working, so it’s especially important to get the issue resolved right away. The rest of this article describes in detail the various causes of a malfunctioning speedometer and odometer and explains how to fix these problems, so if you’re having troubles with your car, keep reading!  

Reasons For a Faulty Speedometer

The speedometer, which is the component in your car that displays the speed you’re going, is one of the most important features of a car. In most vehicles, the speedometer is a circular gauge with an indicator that points to the car’s speed. 

In other cars, the speedometer is digitized, and the speed is displayed as a number that changes with the speed.

There are various reasons why a speedometer might stop working, which is not something to delay fixing. How fast you’re going is one of the most important pieces of information you should know when you’re driving, so you don’t put others in danger, and so you don’t get pulled over for speeding.

Let’s discuss some common causes and fixes. 

Read: Why Speedometer Is Not Working and Transmission Is Not Shifting?

There’s a Problem With the ECU 

The ECU, or the Engine Control Unit, is the center of many engine activities, including reading the vehicle’s speed. If there is something wrong with your ECU, there will be other symptoms beyond your speedometer not working, including: 

  • The check engine light is on. 
  • Your car won’t start. 
  • An unexplained drop in fuel efficiency. 
  • You have problems when shifting gears in an automatic transmission. 

If you notice these symptoms and your speedometer is stuck at zero, that’s a pretty good sign that the Engine Control Unit is to blame. 

If this is the case, you should take your car to a dealership or repair shop that uses the latest computer diagnostic equipment. For the most accurate diagnosis, take your car to a dealership that sells the make and model of your vehicle. 

Unfortunately, ECU repairs and replacements can be expensive, with the part itself costing between $1,000 and $3,000. If the ECU can be reprogrammed, this repair will likely cost you $300 to $700 at a garage. 

If you need to replace the part, not only will you have to pay for the part itself, you’ll also have to tack on an additional $500 to $700 for the cost of labor to install and program the new unit. 

Read: Automatic Transmission Have Grinding Noise When Put in Gear. How To Fix?

Bad Wiring or a Faulty Fuse

If there’s a bad fuse or a bad wire in your car and the speedometer’s fuse stops functioning, the speedometer will drop to zero and stay there. A fuse can blow for various reasons, including a bad wiring job or wires getting wet due to exposure.  

You can take your car to a mechanic to see if this is the issue, or if you’re car-savvy, you can check it yourself and replace the fuse if necessary. 

Here’s how

  1. Ensure that the car is turned completely off. Consult your owner’s manual to find the location of the fuse box. Most fuse boxes have a map near them (usually on the lid) that identifies every fuse and circuit. 
  2. Remove the fuse with a fuse puller. Use a digital multimeter and hold one lead on each prong of the fuse you’re checking. If the reading on your multimeter is “OL,” the fuse is blown and needs to be replaced. 
  3. Remove the broken fuse with care and insert a replacement fuse with the correct amperage. Start the ignition to see if you’ve fixed the problem. 

The following video shows you how to change a blown fuse: 

Your Speed Sensor Is Broken

The speed sensor is one of the most important parts of a car, as it regulates ignition timing, the flow of fuel, indicates the car’s speed, and regulates cruise control. Therefore, a broken speed sensor reduces your ability to drive your vehicle safely. 

Beyond your speedometer not working, here are some other symptoms that your speed sensor is failing: 

  • You’re having transmission problems, including delayed shifts and hard shifts. 
  • You can’t engage cruise control. 
  • The check engine light is on. 
  • You can’t apply your torque converter clutch. 

Speed sensors can become damaged over time due to exposure to the elements and general wear and poor vehicle maintenance. To fix this problem, you’ll need to replace the speed sensor. You can either take your car to a mechanic and have them do it, or you can do it yourself.

Here’s how: 

  1. Park your vehicle, engage the emergency brake, and turn the engine off. Place a vehicle jack on both sides of your car and raise them so you can slide underneath. 
  2. Locate the speed sensor, which is on the right side of the transmission. Unplug the wire and pull the base of the wire connector out of the plug. Unscrew the bolt that secures the sensor in place and remove it.  
  3. Align the new speed sensor and screw it clockwise. Replace the bolt to secure the new sensor into place. 

Consult your car’s owner manual to ensure that you get the correct replacement sensor. Additionally, ensure that you give your car’s parts time to cool down before starting the repair. 

Read: Why Car Makes Noise When Turning at Low Speed?

Why Your Odometer Isn’t Working?

If your speedometer and your odometer aren’t working, the problem is likely one of the causes discussed above. However, if your speedometer is working and your odometer is not, it might be another issue entirely. 

When it’s functioning correctly, an odometer gives you an accurate reading of your car’s mileage, which is essential for a variety of reasons, including your insurance, your ability to sell the car, and knowing when your vehicle needs maintenance work. Therefore, if your odometer is broken, getting it fixed right away is important. 

There is one primary reason why your odometer might be broken, even if your speedometer is fine. 

Read: Why Car Won’t Start but Battery Is Good?

The Gears That Run Your Analog Odometer Broke

Analog odometers, usually found in older cars, are driven by plastic gears that can easily snap. 

These odometers have gears and cables that connect the input and output shafts, and whenever your tires move, the output shaft prompts the cable to spin, which triggers the gears on the odometer to move. 

You’ll need to remove the gauge cluster and replace the plastic gears to fix this issue. You’ll need a flat head screwdriver, a T15, a T 20 tacks, and new gears. 

If you don’t have a screwdriver in your home, I recommend the CRAFTSMAN Screwdriver Set from Amazon. The 5-piece slotted set comes with the flat head screwdriver you’ll need to replace the gears in your odometer, and the blades are heat-treated, so they’re extra strong and durable. 

Once you have all of your materials, follow these steps: 

  1. Disconnect the battery’s negative terminal. 
  2. Unscrew the bolts at the top of the dash. 
  3. Pull the headlight button outwards so you can see the slot on the side of the plastic. 
  4. Use your screwdriver to pry into the clip and remove the switch. 
  5. Remove the gauge cluster.
  6. Replace the old, worn-out gears with your new gears.  

This video shows this process in detail: 

This is most likely why an odometer wouldn’t be working while the speedometer is, so replacing the gears should fix the problem. If it doesn’t, take your car to a mechanic to have them take a look. 

Read: Why Does An Automatic Transmission Have High RPM Before Shifting?

Final Thoughts 

Speedometers and odometers are essential parts of cars, and if yours aren’t working, they should be fixed immediately. Whether you decide to fix it yourself or take it to a mechanic, what’s most important is that they get back to functioning as soon as possible. 

This way, you’ll maintain your status as a safe and responsible driver and car owner!

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