95 Corsa cold starts

Hi,

I have a '95 Corsa 1.4i (auto).

During these very cold temperatures, I have begun to experience problems when starting up.

The car starts OK, but when I put it in reverse (sometimes Drive), it immediately triggers 'limp home mode'. I then have to turn off and start again.

Once the car has been running for a few minutes, the problem stops.

Is this because the sensors have all but frozen, or is it something to do with the gearbox (or something else)?

Thanks.

Neil