I have a 2009 1.2 polo match (N9) If it starts it runs v.well but sometimes it just won't start it's had new spark plugs

and a coil no codes or errors are displayed no dash warning lights. Fuel pump working.

we checked earthing points and cleaned. we inspected connectors to ecu and found them to be clean.

On assembly we tried to start and it did. worked for a couple of days then not starting again.

It hasn't stopped working when the engine has been running and no symptoms when driving.

Any ideas and does anyone know where all the earthing points are.

Oh yes we did take all the plugs out and there was no spark so we think it must be some sort of electrical issue

So hoping somebody has had similar and maybe a solution

Thanks in anticipation Martin

Maybe possibly the battery - had the same issue on a Golf and just not enough current to turn the engine over and power the electronics - once started was fine

Also, check the crankshaft sensor and replace if necessary

I should have mentioned it has a new battery and starter motor and cranks over very well

Ok I make this post to assist anyone who may experience this problem at some time in the future.

We have resolved this problem. We had two keys and it has transpired that one of the keys was defective and triggered the immobiliser so wouldn't start It starts every time with the good key. So hope this may help someone Thanks.