I bought second hand Stilo 1.9 jtd 2004 few days ago and it had "pre-heat error/engine fault" message when I bought it. I thought it was just a glow plug, replaced the dead one. Pre-heat error disappeared but when I start the engine there's still "engine fault" message with that little wrench on display and after some 10 seconds it simply disappears - no showing fault messages during the ride at all. Motor runs smoothly, it starts with no problem, but I noticed that this sign:

glows yellow all the time.

I've read a lot when that sign turns red or blinks but mine just glows yellow and that's it - no other warnings/lamps etc, except this one and "engine fault" short time after motor starts.

Motor runs just fine, no black smoke at all, it pulls right etc. no strange sounds. Should I be worried and should I find good mechanic?

Any piece of advice or opinion will be much appreciated!

you need to get the codes read-isn't it showing any error message on the display??

You could also try disconnecting the battery for a good 30 mins or so, but a garage can clear the error for you-but if it returns, then there is something else wrong.

Thanks for the answer!

The only error message is "engine fault" with small wrench under it on display after I start the car. After some 10-15 seconds message disappears and only that yellow light keeps glowing. And that's it.

I tried removing battery during the night but didn't help.

I'll try to find a good mechanic who can erase previous errors and then I'll see whats going on!

Just a little advice
Get yourself a vag cable and download a copy of FiatEcuScan
You can choose from free version or pay for the full version
If you planning to keep car is worth it as you can read and delete fault codes among all other more technical aspects
You will only need to go to garage if you have to that way

That won't be the problem, I mean the downloading

The only thing that actually bothers me is why in the hell that light glows Yellow!!! I;ve read on bunch of places, here also, that it should glow red or it should go blinking red

Yeah, gotta get myself that piece of software, hook the laptop and see what;s going on. Mechanics here in Croatia usually do not even know how to use those things and closes official Fiat service is some 250 miles from my place

yes, as said, get the software and do it yourself. Running the software should show you the reason for the engine check light, and will certainly allow you to clear the codes