My coolant reservoir was so low that there was less than 8oz of coolant left in the tank. I contacted my local Hyundai dealership and had them service my Santa Cruz. The service techs at the dealership told me that there was a known issue with some of the factory coolant reservoir caps and the seal not working correctly, thus causing coolant to flow out through the cap instead of the overflow hose. They explained that the cap’s o-ring at the factory is sometimes faulty. They replaced my cap and I am still monitoring for further issues. There is no TSB listed for this ‘known’ issue. It seems that the dealership has not reported this issue.