I was inspecting a 2011 Volkswagen Jetta today and saw on my OBD reader that it had two misfire codes, if I remember correctly P0302 cylinder 2 misfire and P0300 multiple cylinder misfire. The check engine light was off. The seller had just mentioned her husband replaced the spark plugs within the last year and I asked if there was something that prompted him to do that. She said that the engine had been misfiring and the problem went away after he replaced the spark plugs.
I wanted to clear the codes and run the engine to see if they came back, but after asking the seller's permission and running my OBD reader's "Erase Codes" function both codes were left. I noticed they were under a heading called "Permanent Codes." Is there any way to erase these codes or are they really meant to be there for the rest of the life of the car?