The code belongs to the radio, not to the car. The VIN and the registration identify the car, so on their own they say nothing about the radio — what links them is the factory record of which unit left the plant in that car.
A dealer can sometimes pull the code from that record using the VIN. It only holds if the radio is still the original: a unit swapped in from another car carries its own code, and the dealer’s answer for your VIN is then wrong. Honda in the US and Canada gives codes on its own site from the VIN together with the radio serial.
We work from the radio’s own serial, so the code is right even for a swapped or second-hand unit. The one exception is the touchscreen on Peugeot, Citroën and DS cars (RT6 and SMEG): there the VIN is what the code is built from, and the brand page takes it.
Opel, Vauxhall and Chevrolet forms accept a VIN too, but we cannot answer those at the moment — you get a plain “not found” at no charge. For every other make, use the serial. Where to find the serial.
Online, only for Peugeot, Citroën and DS RT6 and SMEG screens. Otherwise a dealer can sometimes look it up from the factory record — which is wrong if the radio was ever swapped.
Not from us. A Ford radio code comes from the M or V serial the radio shows on its screen — hold presets 1 and 6.
No — the factory record is for the radio that left the plant in your car. Work from the serial on the unit you have.