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Speed message 107mph after changing speed sensor

I just put a speed sensor on my car because the speed has slowed,my speedometer is going crazy with a speed107mph message.Did the diagnostic and it stated needed that sensor .Now it’s on there nothing has changed.Helppp. I have no lights on the dash.

Maybe the speedometer is kaput.

So you own an Impala. You changed a speed sensor and now you have some kind of problem.

That is all I can get from your post so I can’t help unless you tell me more. What year, mileage, and transmission? What diagnostic? Read codes? What exact code did you read?

Now explain more fully the problem you are seeing.

Instrument clusters go bad, Wiring goes bad, Wire connectors go bad, Control modules go bad.

But Sensors very seldom go bad.

If you can’t provide all the information that @Mustangman asked for, you should have a shop diagnose the problem and fix it.

I have a 2007 chevy impala. 150000 miles. 3.5l,I took it to a mechanic because it is reading speed107mph,the speedometer is going crazy ,the acceleration has stopped at 25 miles per hour. I can still drive the car but it’s slow and it stalls.I had a diagnostic done and the code read p0720 updated speed sensor.I then had it changed the same day but am still having the same problems.I have no check engine lights .

So the speed sensor was bad and now it isn’t since it no longer throws a code.

Clearly you have another problem. The wonky dash sounds like a failing BCM…Body control module. It needs to go to a good repair shop to diagnose if the BCM is bad and if anything else is contributing.