# Unknown Humming Noise

**Source:** https://vwcaliforniaclub.com/threads/unknown-humming-noise.59919/  
**Posts:** 9

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### T — 2025-09-29T21:10:17+0200 (Sep 29, 2025)

My T7 is two months old and it has developed a fault whereby when it is switched off and locked after half an hour a whineing noise appears, which is hard to pinpoint. It is not the water pump or the fridge but it is running down the battery. I had AA out and they said it sounds like a fuel pump running. It has been in the garage a week and they haven't found the fault. I was wondering if anyone here has come across it?

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###  — 2025-09-30T00:09:19+0200 (Sep 30, 2025)

> [Twinw said:](/goto/post?id=761728)
>
> My T7 is two months old and it has developed a fault whereby when it is switched off and locked after half an hour a whineing noise appears, which is hard to pinpoint. It is not the water pump or the fridge but it is running down the battery. I had AA out and they said it sounds like a fuel pump running. It has been in the garage a week and they haven't found the fault. I was wondering if anyone here has come across it?
>
> Click to expand...

Which battery is being run down?  
  
Sounds like an odd fault to not be able to diagnose, I would expect the fault to show up on a diagnostics test.

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### T — 2025-09-30T00:29:53+0200 (Sep 30, 2025)

> [sticky1 said:](/goto/post?id=761749)
>
> Which battery is being run down?  
>   
> Sounds like an odd fault to not be able to diagnose, I would expect the fault to show up on a diagnostics test.
>
> Click to expand...

Main battery second battery no discharge

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###  — 2025-09-30T07:59:54+0200 (Sep 30, 2025)

Consistent? Repeatable? Does it run continuously? So many questions!  
  
Open the bonnet, snap the latch closed with a screwdriver (to fool the car into thinking the bonnet is closed).  
Lock the car. Wait then stick your head in the engine bay and listen.

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###  — 2025-09-30T08:01:34+0200 (Sep 30, 2025)

> [Twinw said:](/goto/post?id=761728)
>
> . It has been in the garage a week and they haven't found the fault.
>
> Click to expand...

You’re surprised?

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###  — 2025-09-30T08:12:49+0200 (Sep 30, 2025)

It would be really interesting to know if this is the widespread cause of starter batteries losing power.   
Whatever is making a noise in yours maybe be silent in others but could be the source of the problem that has been plaguing some owners.   
Have you asked the garage to look at the reports of starter battery issues and want them to apply the software updates and harness change that other people have reported fixed their issue.

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### T — 2025-09-30T08:19:39+0200 (Sep 30, 2025)

I will do so today it's quite possibly this is case as this high pitch sound is difficult to hear and may not be noticed by others who had battery issues.

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### S — 2025-09-30T09:16:42+0200 (Sep 30, 2025)

Could it be the illegal immigrant secreted behind the panelling somewhere who is constantly draining your battery with his mobile phone charging device ![:)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 "Smile    :)")

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### V — 2025-09-30T10:40:47+0200 (Sep 30, 2025)

> [Twinw said:](/goto/post?id=761728)
>
> My T7 is two months old and it has developed a fault whereby when it is switched off and locked after half an hour a whineing noise appears, which is hard to pinpoint. It is not the water pump or the fridge but it is running down the battery. I had AA out and they said it sounds like a fuel pump running. It has been in the garage a week and they haven't found the fault. I was wondering if anyone here has come across it?
>
> Click to expand...

if the vehicle is a PHEV, then it could be the electric water pump for the HV thermal system.

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