FRONT PDC not working QUIET AND SILENT
 

was wondering if any of you can give a suggestion how to proceed from here.
Car : 05 E53 M54 162500 miles no ses.Well maintained.Stock
Symptom: Wife puts car in reverse- gets long beep then beeping stops and PDC button blinking.PDC inoperative
WHAt I did so far: Checked #6 fuse(E53) intact ,swapped with known good fuse.Same long beep on reverse .Still not working,Checked rear sensors with my stethoscope- ALL REAR Sensors have TICKING sound, went to check the front -ALL ARE QUIET and SILENT
Question: could ALL 4 FRONT sensors be bad OR could it be a wiring or software issue?
Any suggestions (general) where to go from here to diagnose the issue?
Thank you in advance .Will post question on Xoutpost too ....

All 4 sensors could be bad if they have been replaced with cheap aftermarket ones. You might have a problem with the connector for the sensors but I think the bumper cover will have to come off to check. There is a ton of diagnostic information on the PDC available if you have a good scan tool.

Sounds like the front PDC loom has become disconnected.

You can check it by removing the right-side fog light - if you have small hands! ;)

I had same issue. Could never solve it by replacing with OE sensors... I finally disabled the frint sensors using NCS Expert. Then I was still getting rear errors, so I grabbed a used module from a pick n pull location adn swapped it in (trunk, by battery compartment) and BOOM, fixed my issues.

RESOLVED
 

thanks for the info,will keep that in mind.
My solution: did a hard reset , did not cure issue , however, for some odd reason , i could hear the 3 front sensors now and was able to pinpoint the defective front drivers PDC sensor...this car just has weird electrical gremlins that i cant explain...
new part ordered(vemo)