I had an accident with my Corsa in February and I smashed the front end in. I got it running but the engine light is permanently on. I have filled it with fluids. Although, for the most part, it idles pretty smoothly, every now and then I hear a ticking noise and the idling revs drop for a second or two and then it is fine again. Could this be a seized rocker, oil pressure, or a plug problem? I know that this particular model can be prone to solenoid problems, could this be one of the reasons?