The way it works.. unusall wheel rotation will indicate a flat tyre. this is sometimes caused by uneven tyre pressure. When this warning comes on then check tyre pressures. Inflate to the correct pressure. Once at the correct pressure, press and hold the flat tyre indicator. drive for a few minutes and the car will retain the information as its normal. If any changes happen outside the new range then the warning will come back on again. eg when you get a flat.
This process needs to be done everytime you change a tyre or put extra air in your tyres. as this will alter your stored settings. Hope that makes sense.

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3.0D Sport Auto, CARBON BLACK! Grey Leather, Smokey Grey Trim, Running boards, auto dim folding mirrors. 6 Disc CD Changer. Tinted windows. 19" style 132 Wheels. PDC.
Sports Pack. 6 Speed Steptronic. Communications Pack - SATNav MKIV, Digital Television tuner with Teletext.