So every time you turn on the ignition, the OBC reveals a shockingly low outside temperature while it goes 'Ding!'?

Well, in that case either your temperature sensor has gone bad or you have faulty wiring.

The first thing to do is to find the sensor. It is located close to one of the front fog lights (drivers side on my LHD). Remove the plastic grilles and look for a small, pointed device. It's connected to a yellow connector with two wires. Once you have found it, simply press it and it drops right out. You should now be able to examine the sensor and find out what's gone bad. Usually it's the wires that's corroded. It was on mine.

Once you have replaced the wires or the sensor, the hardest part still awaits you: patience! The temperature reading rises very, very slowly. It took almost half a day before mine was correct, but if you have done the fix OK, it will get there.