Can I use a 2001 Ford Focus motor in my 2002 Ford Focus?

The Ford Focus wasn’t released into Australia until late 2002, so it’s very unlikely you have a 2001 model unless it’s been privately imported. At which point, all bets are off in this regard as different markets had different models which may or may not be swappable.

But if the two cars are the same model of Focus and aren’t either side of an upgrade, facelift or model change AND provided they used the same engine from the factory (1.8 litre or 2.0 litre) then you should be able to repower one with the other’s engine. The problems would start if one was a 1.8 and the other a 2.0 when you might find that wiring looms, computer software, sensors and even engine mounts might differ from each other, making the swap much harder than it should be. Don’t forget to inform your insurance company and your local registration authorities of the change of engine number.