You can test with a multimeter. Easier with a test harness though so you can take readings while the car is on. But you don't need to do this if you're just moving it and extending wires. Just make sure you use the same gauge/type wiring and like claymore said. It would probably be much easier to do at the sensor end where the wires are clumped together.

Just make sure you take your time and do very good connections.