C4gp high pitch tone from engine bay

[bigbill00]

After turning the engine off I get a high pitch tone from somewhere in the engine bay lasts about 20 to 30 seconds any ideas what this could be
Cheers

[MikeT]

I get the same (C5) and it's just some electronics part (presumably like a stepper motor) going through it's motions.

[bigbill00]

Cheers hadn't heard it before and after having to change the starter as it was knackered was hoping it had nothing to do with that
Feel a bit better now to sort and fault lol

[RichardW]

It's the EGR valve - the ECU cycles it from open to closed to check that it responds correctly over the full range.