I recently had erratic warning lights and immobilizer sometimes not disarming on my S4. Turned out the big square plug in the back had somehow worked its way partially out. One of the rubber bushes/bolts holding the clocks to the front sub frame had sheared. I replaced bush and pushing the plug firmly back in solved the issue, thankfully!
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Roast Beef Monster!
Termignoni and Bucci - Italian for pipe and slippers!
S4 Fogarty, S4R 07T, 748, Series 1 Mirage