news article on spark plug TSB
I think anytime they perform something like this they apply a sticker somewhere on the car advising the correction has been made.At least that's what Honda did back in 1991 when I took my car in for a faulty seat belt connection.
They mark your car with a punch mark to the VIN plate on the firewall. This is the same method they (Honda) use to verify the recall has been applied to any car. It is described in the dealer letter.







