Any thoughts on the ECU issue? It sounds a bit worrying although the Honda garage seems confident that the only issue is that of the faulty injector. I'm pretty sure if there was a way of getting extra cash from me then they would be delighted to do so! I'm thinking that this may be a rare problem and even when they have fixed the injector the other warning lights like EPS and VSA will reappear. I presume when they carry out the diagnostic test that the ECU would report if there was a fault within itself as well as other faults?
ECU damage from faulty injectors is not common, but not unheard of either. If anyone is faced with an expensive ECU replacement, I would recommend considering one of the specialist companies that repair ECUs, such as BBA-Reman or ECUtesting.
Random fault indications are often related to low system voltage - usually a low or failing battery, but can be triggered by a faulty component, such as a shorted sensor or injector.
A diagnostic test may not specifically report a fault that is within the ECU, but where this fault relates to the external interface, you would see error codes related to the running fault that the problem is causing - in the case of a dead injector, you should get an indication of a constant misfire.
IIRC failure of injector outputs is a known fault on the ECU of the mark 2. Really, the suspect injector needs to be tested, rather than the usual "change this and see if it fixes it" approach.