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Steve, BMW Expert
Category: BMW
Satisfied Customers: 25230
Experience:  BMW Expert
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Can anyone help.. I have a 2008 325i touring automatic

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Can anyone help..
I have a 2008 325i touring automatic (petrol),
I have two issues, engine management light is in and has been diagnosed as needing the nox sensor replacing, though have also been told it can be an underlining issue but can't be sure until it's replaced, is this true? The car is underpowered and fuel economy is very poor..
Secondly I have a loud whining when the engine warms up but disappears when I accelerate, I was told it was my crankshaft pulley and have had that replaced today at a cost of over £400 only for the noise to still to be there!!
Just looking for any advice as to what can be done or anything else obvious it can be..
The nox sensor is going to cost but would like to know before I go ahead what the worst case could be.
Hi - is the noise a mechanical whine or more of a whistle?
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Customer: replied 6 months ago.
It's more of a whine, definitely coming from the bonnet and like i say it's constant at low revs and starts after a mile or so and fades when I put my foot down