Thread: Horn sounds when turn key, no ignition.

I have had this happen to me twice now.

I place key in ignition, turn to auxilary and horn sounds very briefly, turn to start engine and nothing happens.

Turn ignition off and try again and all is fine, car starts as normal.

Has anyone had this issue or know the cause.

Battery is low on voltage is usual culprit. Key fob battery low can also not help.

Mine did this and stayed immobilised even after replacing both of these batteries. Needed to clear the BCU fault codes to get it to work.

But usually its the main battery.