Update: after parting with about £600 to replace the booster pipe, the coil light came on again… so, took it back to the same VW dealer. They told me it was now a hose that had broken on the EGR, so could they please have another £1200 to fix that too! Got it done and could feel the difference immediately. Next day, got into my van to go to work and it wouldn’t turn over! Flat battery, which was diagnosed by the AA as being past its useful life. 2018 - 2024 is not a bad innings, so can’t blame it. Another £200 and it was all good to go. Went on a very long drive the following weekend and had no issues with anything at all. I’m back to feeling good again about deciding to buy my T6. And loving the THQ sequential side repeaters I fitted!