Problems with speedometer and rev.

[LuDRaX]

Hello to all saxperience members!
I got 1.4 petrol saxo, 2002 manual. Recently I have encountered 2 problems, probably linked to each other.

The First one is that my speedometer gone crazy, here is the video:
Link (https://youtu.be/7G11p827NKs)
Sometimes it even goes to zero and stays there, get up a bit if I knock the on him.

Second problem, came a day after my speedometer broke, my rev(RPM) are not stable at idle, here is another video:
Link (https://youtu.be/rY8Xmq87vhc)
This one happens randomly, mostly in idle.As you can see in the video sometimes if I give some gas or start driving it would disappear(but not always). My car never got shut down because of that and when it happens I can fill the engine struggling to move the car until he gets to 3000 rev.My check engine light only blinks when this problems occurs, otherwise it is off.
I got and simple OBD2 tool scan and it shows me problem code P0200(link (http://www.obd-codes.com/p0200))

Does anyone knows what can cause the problem? did anyone encountered this before?

p.s - I replaced the fuel filter, air filter and oil to new ones.

[stevo67]

With the car running what's the battery voltage reading?

[LuDRaX]

I checked with my multimeter and it says 14.2 V - so that's normal(car off is 12.75 V).
forgot to mention I got 2 6X9 morel speakers connected with massive audio digital amp.

[stevo67]

Disconnect the amp and see what happens.

[LuDRaX]

disconnected the amp but the problem on obd2 reader still exist, and didn't encountered the problem yet, will have to drive some more.
PS - I was riding my car for over than 2 months with amp and everything was fine so I don't think it is related.

[stevo67]

Until you clear the fault on the ecu the code will keep on re-appearing.