3 Symptoms of a Bad Speed Sensor (Engine or Vehicle Speed)

Last Updated on December 13, 2021

There are two common types of vehicle speed sensors and they each play a different role. One type, the engine speed sensor (or transmission speed sensor) is usually installed on the transmission or transaxle. The other type, wheel speed sensor (or vehicle speed sensor) is installed on the knuckle arm on the four wheels.

The engine speed sensor takes data from crankshaft position sensor that give information for the engine spin speed. Vehicle speed data comes from the speed sensor which is located on the wheels and sends information regarding wheel spin speed.

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Therefore, any fault from either speed sensor or any symptoms showing how defective it has become can lead to a wide range of abnormal problems in your vehicle if you fail to pay attention to it in time.

Common Bad Speed Sensor Symptoms

#1 – Rough Gear Changes

incorrect transmission shifting

One of the most common speed sensor symptoms of your car is that the transmission will not smoothly change gears of your vehicle because of higher transmission revs. This means that the car engine runs at higher speeds than the car itself.

You may also find it very rough while shifting gears and as the problem worsens, you will find it unbearable to change the car into higher gears. This means that the vehicle’s transmission will eventually engage into overdrive very late.

Why Does This Happen?

The transmission of your vehicle can only shift smoothly with the help of a healthy speed sensor. This sensor counts the number of internal revolutions in the transmission. Consequently, the control unit of the transmission receives the data then makes the necessary adjustments after calculating the rotational speed.

Unfortunately, it is impossible to repair the transmission speed sensor as it simply fails. You have to discard it and replace it with a new one. A professional mechanic should help you examine and diagnose the speed sensor system of your vehicle even though the symptoms may seem similar in all cars.

#2 – Speedometer Malfunction

speedometer not working

Once the vehicle’s speedometer stops functioning all of a sudden, this is a sure fire sign that indicates the speed sensor has become defective. The malfunctioning speed sensor means that the speedometer will not have the ability to display the speed your vehicle is traveling at.

Not knowing how fast you are going is obviously concerning especially when there is little other traffic on the road to help you at least estimate your speed. This can land you in trouble with the authorities or even cause unnecessary and avoidable accidents.

#3 – Check Engine Light On

check engine light

Furthermore, sometimes the check engine light may light up recurrently and periodically as you accelerate without any good reason.

To understand what the check engine light means, you should use diagnostic tool or car OBD scanner to get the trouble code(s) which will help troubleshoot the issue. For example, DTC P0500 (Vehicle Speed Sensor Fault Conditions) may appear to confirm the issue.

See Also: Ford AdvanceTrac Problems

Conclusion

Many problems can arise if your vehicle has a faulty speed sensor. Indeed, a car that shows the symptoms of a worn-out speed sensor can bring about other related symptoms to other parts of the car, such as a faulty throttle position sensor or even a malfunctioning coil pack.

Faulty speed sensor symptoms come with some common characteristics that can affect your car engine and its related components.

And finally, any of the above speed sensor symptoms should prompt you to take your vehicle to an auto repair shop or trustworthy mechanic so that they can run a computer diagnostic on your car to identify the faults.

Even though some of the above symptoms may point towards a malfunctioning transmission, it is advisable to visit a repair shop having the best computer diagnostic equipment even before visiting a repair shop specializing on speed sensors to ascertain the real problems.

 

37 thoughts on “3 Symptoms of a Bad Speed Sensor (Engine or Vehicle Speed)”

  1. I have a 2000 dodge neon and when you have it started and your foot on the patel and take it off it shunts off and the rpm gauges dont work i need help.

    Reply
  2. I have a 91 ford f150 automatic it will run good then it will get where it will not pull park it for 2 days and it will run good again

    Reply
  3. i have a 2004 mercedez c240. My gear will not change even after a long drive i have changed my faulty speed sensors but the problem still remains. do i also change the back axle shaft.

    Reply
  4. I have a 2007 Toyota Camry. I had to have a Jump start yesterday and when I got it, I went to go take off in my car and it wouldnt move. My foot was on accelerator and the rpm would only got 5o 2 and the idle only would go ton15 mph by itself. Accelerator wouldnt work. I changed battery and checked all fuses. And I tried to reset it like I was showed on you tube. Still nothing what could be wrong

    Reply
    • It shouldn’t damage the speed sensor but towing a rear-wheel drive vehicle backwards is just asking for trouble since the front wheels are made for turning. It could fishtail or you could break the steering linkage. The correct way would be to disconnect the driveshaft and tow with the front wheels on a dolly or simply use a flatbed trailer.

      Reply
  5. We have a 2006 Nissan titan 2 wheel drive we’ve fixed the speed sensor inside of transmission and one on the side which i think is the output sensor and it’s still acting up. Once on the hwy when we hit 60 mph it sounds kind of loud and when barley taking off we feel a grinding noise and it’s burning oil from the engine like crazy do u know if there’s another sensor?

    Reply
    • Check whether there is any cables broken near the wheel base. It usually happens when the un-professional mechanics doing these kinds of jobs., They wont care about the cables or sensor parts installed on it. By pushing forcefully removing the wheel base for brake pads its cause to breaks. Its my personal experience. I did myself to trace the cables and joined with connectors. Problem solved.

      Reply
  6. I have vw polo BUD engine,while on the road I find it closing very fast and yet I haven’t pressed the accelerator.What could be the solution to this problem

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    • It could be a vacuum leak that’s allowing more air into the engine, or an issue with the throttle to name a couple things. I would get it addressed as soon as possible. Unintended acceleration can be very dangerous.

      Reply
  7. I have a 2006 toyota camry v6 3.0 it saying did a diagnostic at auto zone its saying bad knock sensors and bad speed sensor and my car shakes when I drive over 60 and when I use my GPS my speedometer will say 65 but my GPS says my car is going 60. So do I need to change the speed sensor or knock sensors or both

    Reply
    • That’s not something that can really be diagnosed over the internet. You’ll have to have a mechanic look at your car in person to determine what needs to be replaced.

      Reply
  8. my 1998 ford explorer speedometer stopped working then works then stops. why would it work off and on. is there a way to fix it

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    • It sounds like your vehicle speed sensor is going out, or you possibly have a grounding or wiring issue with the wires that lead to the sensor. Intermittent issues like that are often electrical in nature. It should be fixable, but you’ll have to have someone take a look at it to know for sure.

      Reply
  9. I have a 2002 Hyundai Elantra gls and when I put it in drive it stalls out but when I put it in reverse it drives fine. Can this be a transmission speed sensor issue. Can anyone help me with this problem. Thank you.

    Reply
    • It’s probably not the speed sensor. I would look at your idle air control valve. You might need to look deeper into the transmission, though.

      Reply
  10. I have 2003 chevy s10 zr2 4×4. I’ve replaced my vehicle speed sensor three times now. It will work fine for a bit but after a couple months its time to replace it again. Any insite?

    Reply
    • Do you still have the sensors you replaced? I would inspect those to see if there is any damage to the sensor or anything suspicious with the wiring.

      Reply
  11. hello my vehicle fiesta 2006 1.4 petrol. Could the speed sensor I want to ask cause p0420 failure? I have one more problem, my vehicle is running very loud. Does the speed sensor have an effect on the noisy operation?

    Reply
    • No, it shouldn’t affect either of those things. P0420 is a catalytic converter efficiency code. I’m guessing the loud operation is due to an exhaust leak. The loud operation and P0420 may be related, though. You’ll have to have the exhaust system inspected to determine where the leak is, and do a bit more diagnostics on the catalytic converter operation.

      Reply
  12. I hv a chrysler voyager 3.3L v6 my problem is power wen I Rev it de revs doesn’t even reach 2rpm it stops under 2, cn it b a speed sensor problem?

    Reply
    • At wide open throttle the tachometer won’t exceed 2k RPM while you’re standing still? I doubt it’s the speed sensor.

      Is your check engine light on? What are the codes?

      Reply
  13. Engine light always on
    Speedomiter dont work anymore
    Abs and brake light always on
    Idle runs low and erratic
    Stalls in drive/park
    Transmission skips randomly like its missing a gear.

    04 dodge ram 1500

    Reply
  14. I have a 2006 infiniti suv, the engine broke down so i had to replace with a new engine but after doing that the automatic gear wont move at d when the engine is cold so i had to move it with g1 before it moves then return back to D then it engage when the engine is hot. how do i fix the problem

    Reply
    • I am not sure. Check the factory service manual for the vehicle to see if there is a step you missed, or a specific troubleshooting step to take in this scenario.

      Reply
  15. Hi I have a 2013 Chevy equinox the trouble I’m having is with the transmission I believe. I recently had the tranny flushed. Check engine light is on. Reading code po700. It’s saying That could be numerous things. Just wondering if the Tcm needs replaced

    Reply
    • I don’t know. It could be the TCM, or the wiring leading to the TCM, or even a fault with the transmission itself. More diagnostics are needed to be able to say definitively.

      Reply
  16. I have Chevy Tahoe 2005. Engine works when shift the gear to drive vehicle doesn’t move what is the possible reason?

    Reply

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