When mine is left idling it will get up to those sort of temperatures.

I fitted a coolant temperature gauge to mine to help keep an eye on things. I don't trust a warning light - even when they're working they generally come on after it's too late.

When I set it up I measured the gauge against ECU temperature readings and produced a table (which I will attach below). It shows that at idle mine peaks at 103C, fan cuts in at 102C and cuts out at 95C. I only ever see these sort of temperatures in the real world when stuck in heavy traffic on a hot day.

If yours is reaching 103 and you can't hear the fan cutting in then something isn't quite right. As WmcQ says, connect the fan direct to a 12V supply and see if it operates first. Also check the coolant level, concentration and whether the radiator cap (prone to leaking) is holding pressure. Even a slight pressure drop in the system will cause a significant increase in operating temperature. Air locks caused by low coolant levels can cause bad circulation and hot/cold spots.

Are you testing the coolant temperature in the DIAG mode in the dash?

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