Electrics problem with the ECT2 sensor

[kit86]

Right, here goes. Im new to this forum so bare with me if im posting in the wrong area. I've recent acquired via private trade an 55 plate ES 1.8 petrol civic. its all good as it's always been my dream to get the civic. but in less than 2 weeks. the ECU light came on. so took it to a honda garage in manchester n had it diagnostic checked. dealer said to me it was a rare problem however, it was nothing major and it just needs an ETC2 sensor changing that will cost me 100 squids. well i'm now back at home in midlands. and i rung up another honda dealer explaining the situation. they then told me that its a 'common' problem and that the guy dealt with at least a dozen over silimiar cases which then he says. all require a wiring loom to be changed which will cost me a minimum of 1k!!! has anyone else had any kind of similar problem? and which honda garage do u think i should trust? any form of advise is much appreciated as i am now worried sick about the car
(also does anyone know what the ETC2 sensor actually is or do? i've just been told its basically a temperature gauge by the dealer)