This is my first forum post - sorry in advance if I don't provide all necessary information, but I'll do my best.

I have a 2012 XC70. Base model, AWD, not T5.

Often, after I shut the car down, the engine will whine for a few minutes. It almost sounds like a very faint whine from the horn, but I cannot be sure of the source.

This has been going on for many months, and does not seem to be negatively impacting anything else. I even brought the car into the dealer to have a belt replaced, and they either ignored the issue or could not find the cause.

Any ideas what may be causing this?

 

Hi

It may be the PCV trap clogged , after you stop the engine take out the engine oil dipstick, if the sound stop , it is the PCV clogged.

best Regards

 

is the fan running? in warm weather the fan can run for a few minutes. have you opened the hood and looked around?

 

It could be the power steering system. Sometimes, air trapped in the system can cause a whining noise after the engine is turned off. Also, check the transmission fluid level and condition.
If those don't seem to be the culprit, maybe inspect the alternator or even the cooling system.