i have exaclty the same problem on my IX. Havent dealt with it yet though.
Many European IX's have the same issue.
After searching on the American evo forums I found out that you can try the following:
-Clean the thottle body/idle control valve to remove carbon deposits
-Check throttle body for leaks(dont think it leaks on mine because the idle is ok. I just have the CEL)
-Increase the steps in the idle control valve via the ECU. I read that anything from 2 to 25 is OK. This can be done in your mitsu dealer.
-Try to manually increase idle to 900 rpm.
-Others reported that installing cams resolves the issue which is funny.
Hope this helps but I would like some more suggestions because I want to deal with this as well.
Merlin, where did you have it remapped? Same thing happened to me, intermittent at best but annoying non the less.
A battery off for 1/2 an hour will reset the light and the code log....but mine was finally corrected with a new map and newer level of ECUTEK firmware (sorry but don't know the version no.)
i cleaned my Throttle body and intake manifold with carb cleaner and the idle has increased a bit resulting in the same CEL. Hopefully when the cleaner evaporates the idle will get back to normal and the CEL will dissappear...fingers crossed.