Its possible that your car wasn't originally fitted with a sump sensor and the sump was swapped out with one that had the sensor... typically the sump sensor is for cars that have a full DIS in the cluster
As for your dipstick issue... oil will wash up the dipstick tube from normal driving... this is why you always wipe the dipstick first and take the reading from a clean stick... if this is not showing oil then basically you have low oil levels and need to top it up...
This is also assuming that the dipstick tube is correctly fitted and not damaged as I have seen this before when someone added a bit of silicon tube to fix a broken tube and effectively changed the level the dipstick sat in the sump and subsequently changed where the level of oil was read from meaning they had less oil in the sump than was recommended
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