Just a quick post as this may save someone some head scratching. Had a Matiz brought in for lack of power when started, customer could'nt drive away for a minute or so, when warm it ran like a dog.

Connected scanner and got-
1/ P0406 egr sensor 'A' circuit high.
2/ p1403 Man. spec. code.
3/ p0122 tps 'A' high circuit high

Customer also mentioned that fuel gauge not working.

Cutting a long and much scopeing and probing story short, if you unplugged the egr valve the fuel gauge worked !, the egr valve was shorting out internally and earthing the 5V signal which was robbing the feed to the other 5v fed sensors,
path of least resistance and all that !.

New valve fitted, no more problems.

So rough running matiz with no fuel gauge... unplug egr valve and just maybe...!

Hope this may be of use to someone.

Mark Bundy