ECU fault codes

[FFMan]

It seems to me there fault code readers are expensive for what they are, even the BITS ones aren't cheap compared to ones you can get in Halfords for other cars.

I wonder why the cost is more, supply and demand or are they more complex ?

It seems to be (and I have done a bit of PIC programming) that its just a job of decoding some serial or digital signals, and once you know the format it won't bee too hard.

Does anyone have any info about how the fault code is transmitted ?

[Pupp]

I've got a BITS one and don't think it was expensive at all considering the answer to your Q has been sussed, the circuit has been designed, tested and built, it has been cased, interfaced and documented. Oh, and works

[blitzracing]

Its serial data, but I dont know any more. You certainly cant access the ECU / Eprom maps through it. You need the Lucas Development unit for this, and they are as rare as Rocking Horse poo.