Ok, where to start

About 2 weeks ago we had in Ireland a major cold spell and about halfway through my Octavia refused to start , i checked all the obvious things like that the air filter was ok spark plugs were dry and i even replaced the battery .

When i hop in to start it the engline rev's up and then just knocks off again and will rev on starting all day long but will not start, if i keep the key turned it makes a jumping/hiccuping sound.

I am beyond my technical knowledge here and would just like an idea of whats wrong before i take it to a garage to get looked at , thanks in advance for any replies.

P.S. There is a symbol on the dash i have never seen before of a Car with a key symbol as the chassis between the front and rear wheels(came on after i jumped started the old battery the 1st time)

The symbol you are seeing is the immobilser warning light. The car will start, run for 2 seconds and then stop.

Do you have another key you can try?

Try another key, if that works then the immo chip in your key has broken or the ecu has lost its pairing to the key. If the other key does not work, then its possible that the transponder pickup in the car has failed or is failing if the problem is intermittent. Both are relatively straight forward to sort, but will involve a dealer visit.

It may be the loom between the transponder pickup and the dash which has failed. This is probably the cheapest and easiest place to start your investigations, assuming a secondary key does not work.

Sorry i forgot to mention above, i tried both keys and it's the same thing :(

I also checked the fuses today as the driverside window motor has stopped working