Skip the auto shop - Our mechanics make house calls

Q: Speedometer is erratic and the S light is on

asked by on

My speedometer jumps up and down and then stops working. Then the S light comes on. There is no loss in power and the transmission seems to shift properly. I have noticed it usually does this after the 2nd start of the car. If you turn the car off it goes out and the speedometer works fine again.

My car has 139000 miles.
My car has an automatic transmission.

There are a few different components that can cause these issues. The main one is the vehicle speed sensor (VSS). This is located on your transmission, and communicates to the engine what speed the transmission is receiving. The VSS also sends important information to your vehicle’s computer, and this information eventually ends up on your dashboard.

The first thing you should do is have the vehicle scanned for codes. You will want to make the symptoms occur when running the test. This way, the scanner will be able to list what components are setting the warning light, and help you confirm or deny the VSS as the problem. I recommend having a professional mechanic, such as one from YourMechanic, complete an inspection to determine if there are electrical problems and why the speedometer is not working correctly.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: engine cranks over but won't start

Hello. Thank you for writing in. The fuel smell you are having is from the engine throwing fuel into the cylinders that is not being burned. The spark system will is likely the cause of your no start. If none...

Q: My car is not getting fuel to injectors I replaced filter and fuel pump

Hello, from what you describe it appears that you may be having an issue with the engine management system. The fuel pump provides the fuel and pressure for the fuel injectors, however it does not control their on and off...

Q: The AWD disable light is on in my 2006 Buick Rendezvous

Some systems require more than a code reader to find a fault. The AWD disable light means that there is a fault with that system. The AWD system controls torque (rotational force) to the four wheels. This is to improve...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...