I always garage the car every evening. Normally after I have locked the doors I hear a high pitched noise for a few seconds then a click like a relay firing and the noise stops.

On the odd time I have noticed this whistle / whine doesn’t stop. or some time later I have returned to the garage and I can hear a noise coming from the car, the only way to stop this it is to turn on the ignition then off again. This has happened only about 8 times over the last two and a half years. (There again my wife can’t hear it so it may have happened more) Also if the car is parked on a busy street I may not hear the sound due to traffic noise. Any ideas please

Does it make the noise is you don't lock the doors?

Where is the noise coming from?

I've never know a car to make as many strange noises as my Octy.

I've had a high pitched 'sqeak' from the engine after it was switched off. That was weird, it would squeak, pause squeak and the gap between the sqeaks got bigger until it stopped.

I've only hear that once and nothing has gone wrong with the car. It was like air escaping but I've not a clue where from.

Yesterday sitting with the engine off something behind the dash was making a noise like the brain of Robbie the robot or a mechanical typewriter.

Again nothing wrong with the car it just makes a lot of odd noises when the engine is off.

The noise you're referring to is made by the auxillary coolant pump. It cools the turbo after you've switched the engine off to help extend its life. It sounds like a high pitched whine.

Its perfectly normal for it to run for a short time after the engine has been switched off, particularly if you've been working it a bit, although I've never heard it run on for ages like you have said.

Thanks for the replies. It has only happened a few times in the last couple of years.

Usually at an inconvenient time to investigate. The last time was a couple of nights ago, we had been out to a concert the temperature was below zero and it was after midnight. We had only driven about 6 miles and due to the icy conditions I doubt if I had got above 40mph. I returned to the garage about 5 minutes later to get something and I could hear the noise still going. Turning the ignition key to on (not starting the engine) then off again immediately stops the noise. I will try to investigate further next time it occurs.