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Q: My speedometer intermittently works at about 1/2 speed.

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Usually when first starting out the speedometer reads about 1/2 speed. Then usually along the way it starts working. There are no transmission issues. Shifts fine. Could this be a front wheel speed/ABS sensor?

My car has 130000 miles.
My car has an automatic transmission.

A: As long as there is nothing wrong with the ...

As long as there is nothing wrong with the transmission, it would have to be a problem with either the speedometer drive cable, or the speedometer head unit. The drive cable is driven off of a gear in the transmission and transmits the speed of the transmission to the speedometer head unit in the instrument cluster. The sensors mounted to the wheels is typically used by the anti-lock brake system to monitor the relationship between vehicle speed, and the speed at the wheel, so the computer can tell whether or not a wheel is locking up during braking, and needs to pulse the brakes. To avoid any unnecessary repairs, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose the issue with your speedometer.

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