The IPDM units do fail due to water ingress and I have changed out lots of them. They are sometimes misdiagnosed as the car needing an ecu. The gromit underneath the IPDM can get dislodged and let water in. I have never seen it damage a loom but if it was severe water ingress then water can damage the plugs etc. Where are you based? It may be worth you getting a second opinion here. PM sent
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