I have a 2004 3.9 V6 mustang. It had a sqeaking sound. I took it to the shop several times and replaced the belt, tensioner arm, water pump, ac compressor and alternator. The steady squeak is gone, but now it has a loud screeching sound that comes every 5-10 minutes. There is also a Service Engine light on that says something is wrong with the crank sensor. My mechanic says the crank sensor is fine. Any ideas what it could be?
 
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Always post the full DTC code. There are 1000's and they each have a story to tell. Almost all auto parts stores will down load for free. So there's no excuse not to post the full DTC codes.

I doubt the DTC says there's a problem with the crank sensor (CKP). Why? Because the motor would not run at all.

If looking for a WAG about what might be wrong, then a bad camshaft synchronizer sensor (CMP) bearing. It is a common problem with the V6.

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https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

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Here's some other threads about the subject.

https://www.allfordmustangs.com/forums/v6-tech/190583-replacing-camshaft-synchronizer-sensor.html
 
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