Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. Symptoms of a Bad or Failing Speedometer Sensor

Symptoms of a Bad or Failing Speedometer Sensor

speedometer sensor

The electronics in today's cars and trucks are extremely complex. However, one of the simplest devices we rely on to deliver us factual data is the speedometer. Essentially, the speedometer is powered by three independent components; the speedometer on the dashboard, the cable attached from the speedometer to the driveshaft and the speedometer sensors attached to the driveshaft to measure speed. Some speedometer issues are due to dirty or faulty sensors that relay false data through the cable and eventually show up on the dashboard.

Where is the speedometer sensor located?

The speedometer sensor is located in the transmission of your vehicle and is designed to register the driveshaft’s rotational speed. The sensor delivers this information through the speedometer cable and to the vehicle’s computer, which converts electrical pulses into a numerical speed. Eventually that number is displayed on the speedometer and tells you precisely how fast you are driving. If the speedometer sensor is not working properly, the speedometer will be inaccurate; potentially leading to speeding tickets or unsafe driving situations.

The symptoms noted below will give you an indication that a problem exists with your speedometer sensor:

1. Speedometer does not work

Whether you have a digital or manual speedometer, if it's not displaying accurate information, it doesn't really help you. One of the biggest signs your speedometer sensor is not working properly is the speedometer will display inaccurate readings or the needle or digital numbers will not move at all on the speedometer display. A malfunctioning speedometer sensor can also cause a speedometer to act erratically, fluctuating the reading from one speed to another; even though in reality you're not speeding up or slowing down.

If you feel you are driving faster or slower than what the speedometer reads, it is a good idea to have your vehicle inspected by Your Mechanic, as this might be a problem with the sensor that can be repaired or an indication that the speedometer sensor needs replacement. Being proactive about repairing your speedometer issue can improve safety, not only for you, but others on the road. It can also reduce the potential of getting two citations; one for speeding and another for a damaged speedometer.

2. Cruise control does not work

The speedometer sensor is also a critical component in the proper operation of a vehicle’s cruise control. When the sensor is not working correctly, it will not send a signal to the CPU, which impacts the vehicle’s ability to set the throttle for a desired speed. As a safety measure, automotive manufacturers engineer the cruise control in a way that if the speedometer sensor is acting up, it won't engage the cruise control at all. On most cars sold today, this will be indicated by the cruise control light being illuminated on the dashboard - even if it's not engaged. If you experience this problem, it's possible that the speedometer sensor needs to be replaced.

3. Check Engine Light comes on

The speedometer sensor is located inside the transmission and attached to a driveshaft, which impacts multiple functions of the car. Due to this fact, it's possible that the Check Engine Light will light up on the dashboard if a sensor problem is discovered by the vehicle's CPU. Regardless of why the check engine light is illuminated, it's never a good thing, nor should it be avoided. If the check engine light shows up anytime, contact a mechanic as soon as possible so they can diagnose the problem with the correct diagnostic tools. Sometimes the issue is small and the CPU needs to be reset; but don't take that risk.

4. Vehicle loses power

Today's cars and trucks have electronic fuel injection, which is controlled by the onboard computer. The EFI supplies fuel to the engine based on input from multiple sensors; one of which is the speedometer sensor. If you notice that your car starts to lose power; especially when you apply pressure to the throttle, this might be caused by a damaged or malfunctioning speedometer sensor. This problem could be potentially harmful to other mechanical components on your vehicle, so don't ignore the issue. Contact a certified mechanic as soon as possible to determine what is causing this issue.

As you can see, the speedometer sensor impacts the operation of multiple components that allows you to efficiently operate your car or truck. Anytime you experience any of the above warning signs, contact a professional mechanic to properly diagnose and repair the issue.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
P0359 OBD-II Trouble Code: Ignition Coil I Primary/Secondary Circuit Malfunction
P0359 code definition The P0359 code indicates that a fault has been detected in one of the vehicle’s ignition coils, generally the number 9 coil. This code can also be associated...
P0608 OBD-II Trouble Code: Control Module VSS Output "A" Malfunction
P0608 means there is an malfunction in the vehicle speed sensor A control module often due too faulty speed sensor or shorted electrical wiring.

Related questions

Q: Having trouble trying to locate my knock sensor. It's throwing a code for it. 1,2,4,5,6 cylinder misfires

As you may know a knock sensor may fail for any of the following reasons: The knock sensor is faulty and needs to be replaced There is a wiring open/short/fault in the knock sensor circuit The PCM/ECM has failed...

Q: Replaced rear seal and now I Only have first gear and my speedamater don't work.

If you replaced the tail shaft seal behind the yoke and had to remove the driveshaft, then it is possible that the transmission vehicle speed sensor VSS is not installed correctly or the harness has been damaged. This will make...

Q: when driving speed slow down and resume to speed it begins to jerk i have to put in over drive to resume speed especially on hiway

You should have the vehicle scanned. The data from the speed sensor needs to be checked to see if the transmission or engine is the cause of the jerking. You may have a transmission solenoid that's not shifting correctly, an...