The shop (or you) can sometimes silicone around the leak. I have a 2006 D12 and that’s what had been done to mine. It still leaked but the head mechanic at the Volvo dealership I use said he would continue to drive it until it started leaking more. I replaced it at the next PM which was a year later. It’s costly a couple of thousand I think. They do make a patch kit to help keep it from leaking into the ECM. Early this year I had to replace my ECM and when they opened the back it had water and oil in it but also the sealant around the back plate of the ECM was deteriorated, crumbling and had gaps. My thoughts are the original “leaking” harness was not the culprit just old sealant. In summary, you pay your money and take your chances but in all likelihood will be fine until you can replace it. What I would recommend is, if you are mechanically minded, remove your ECM and look at the sealant on the back and reseal if necessary. OTR performance has a video on YouTube titled “Volvo Truck/Replacing ECM on D12”. Doesn’t look like a hard job. Might want to review this thread for the repair kit