In the manual gearbox of the early Fabia the synchro rings wear out: second gear binds or "crunches" when cold, later third does too. At first you only have to shift more slowly, and finally the gear will not go in at all. On a car used heavily as a driving school vehicle the synchros wear sooner, and a gearbox rebuild on a car in this price bracket can easily take half the value of the car.
What to check
- Shift into second cold several times, quickly too: crunching means a synchro fault
- Try the 2 to 3 and 3 to 2 shifts while driving, under load as well
- Watch whether the gear jumps out on its own when lifting off