Skip the auto shop - Our mechanics make house calls

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
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

Post a question and get free advice from our certified mechanics.

ASK A QUESTION

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222 code means The manufacturer specifies a range of acceptable voltage to be produced from the throttle position...
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...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...


Related questions

Q: Is it safe to drive when this warning light is on? Thanks.

The Advancetrac is the name for your traction control system that is used by Ford. The traction control system monitors the steering stability of the vehicle and engages when loss of traction has been detected. This is done by the...

Q: Cooling fan unresponsive and other electrical issues - 1995 Dodge Spirit

Hello. It sounds like you have an issue with a bad electrical connection. Most of the time, this occurs from either a bad connection at the battery or a bad negative battery connection. The negative connections at the body and...

Q: Venza 2010 L4-2.7L: My check engine light is permanently turned On. I have these codes P0012, P0016, P0017. What needs to be fixe

These are fault codes indicating problems related to the timing of your car's engine. Normally the car will not run very well or sometimes not at all when these are on. I would suggest having an expert from YourMechanic come...