Q: Speedometer fluctuating

asked by on January 26, 2017

when slowly accelerating, the speedometer does not automatically start reading, it starts late and when you speed, the actual speed is not the same as the one on the speedometer and after speeding for about 1 minute, the speedometer drops to 0

My car has 171000 miles.
My car has an automatic transmission.

Instrument Voltage Regulator Replacement $204.37 - $364.61 Get a Quote
Speed Sensor Replacement $92.92 - $1189.26 Get a Quote

Hi There, This could be related to a couple of possibilities. The [instrument voltage regulator]((https://www.yourmechanic.com/services/instrument-voltage-regulator-replacement) regulates the voltage supplied to the various gauges in your vehicle’s dash. When this is not working properly, this may cause the gauges in your dash to dim or flicker erratically or in some cases provide false readings.

This may also be caused by a faulty transmission speed sensor. The speed sensor reads the rotational speed of the reluctor wheel, located within the transmission. The speed sensor also controls the anti-lock braking system. Driving with a bad speed sensor usually causes the ABS to malfunction and can lead to loss of braking power and/or an accident. When this is not working properly, you may also notice the transmission hesitating to shift gears, erratic tachometer readings, the speedometer not working properly or the odometer not working properly. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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