G7 Engine Management Diagnostics

[DefiantFrog]

Every now and again I get the engine management light pop on, then after a couple of days it will go again. I'm not particularly concerned - the car is behaving absolutely fine (if not better than ever!) its just annoying that for a couple of days I get a glaring orange light. I keep booking in at Toyota for them to check it out, but by the time the appointment comes round, the light is out again, and diagnostics comes up with nothing (and I have to be impressed with Inchcape Notts here, as its been in twice now, checks run and full valet, and they haven't charged me a penny!).

So, questions are... Has anyone had a similar (but diagnosed!) experience, and what was the cause? I am pretty certain its nothing more than a failing sensor, it'd just be nice to know and get it sorted. And, is there any way of me diagnosing it myself when the light is on as Toyota can't get me in quick enough?

[japracer]

could be right about the sensor but more likely there's corrosion in the plugs of the senors this is why the turn the em light on, is it effected more on hot or cold days, this would probally help, so the easy thing to do is buy some wd-40 or moisture remover and unplug every sensor plug, spray the wd-40 or moisture remover in the plug and close and open the plug a few times, if this doesn't work or in the process check which plug's make the engine management light come on, hope this help you'r prob