Monster S4RS 2006 weird issues

[sammute]

Hello!
I am having some weird issues 
First - ECU shows rpm on idle about 1380rpm, while tacho indicator goes up and down between 1400 and 1600. Is it usual?
Second - tacho shows temperature about 7 C degrees higher than ECU.
Third - after a while, no matter if the engine is hot or cold, check engine lights on. ECU sometimes shows no error, sometimes reports open circuit of left fan. At about 105 degrees fans turn on, but the temperature is still rising till I open the throttle.
Tacho is brand new, there is a full Termi kit.
Please help! I love this Monster but it turns me crazy with these issues.

Greetings, Chris

[Speeddog]

There are two temp sensors, each mounted on a different cylinder, temp gauge on the instrument panel uses one, ECU uses the other.
So they'll likely never read the same.

When you turn the key on, the gauges sweep, then return to 'zero'.
At that time, engine not running, is the tacho actually at zero?

It is an analog gauge, and ~2 needle widths is about 200 rpm.
I wouldn't consider it a significant error.

In that test condition, temp will continue to rise with engine at idle.
The cooling system is not sufficient to control temp indefinitely at idle.
Opening the throttle moves more water, and cools the motor.

Try disconnecting/connecting the connector on that fan a couple times.
It is prudent to track down whe the CE light is coming on, even if only to eliminate false positives.