Speedometer sensor were is a speedometer sensor in a 2001 galant?

the camshaft position sensor is located behind the harmonice balancer remove balancer and timing cover once removed you will see it u will also have to remove the crank gear and timing belt be sure to reset the timing or mark the gears before removal hope this helps

You found out the hard way that all the electronics in newer cars are lijnked togeather, my advice replace the radio with the factory unit.

it means the engine needs to be servised it works on milage traveled

the vehicle is in limp mode" you will have get a good scan tool to check trans codes or take it the dealer, better choice

The speedometer cable could be broken or loose. The speed sensor is prbly your problem. Do you have a tachometer? If so does it still work?

on the fuel supply rail to the injectors under the hood on the top of the engine.

Most cars have one main vehicle speed sensor (vss). The VSS in front wheel drive cars is mounted in the transmission. A gear in the tranny turns a small gear on the VSS. If a tooth of the gear on the VSS is damaged, you can get that erratic speedometer jumping like you're experiencing. A malfunctioning VSS can cause problems with shifting and with the activation of the anti-lock braking system and cruise control. Have a Transmission shop inspect your VSS and replace if necessary, if your handy with tools. you can buy the VSS and replace you self. The speed sensors on the Galant are called pulse generators and need to be replace as a set. Located outside of the transmission right on top.
Good luck!

seams to be wrong sensor ,or the instrument is defective

The CMP sensor is mounted on the left end{opposite end from the timing belt}of the cylinder head...

Its located in the air filter housing....The volume air flow sensor also incorporates the barometric pressure sensor and the air intake sensor....If you are replacing either of these sensors replace the volume airflow sensor.......