DL360G8 displays fan failure in fan slot4 only.

I have a customer with an HP ProLiant DL360 G8 server that displays fan failure in fan Slot 4 but fans that have be inserted in that slot seem to be functioning normally. I've inserted a new fan and swapped fans around in the system in and out of that slot but it still reports failures and there's no temperature issues have been reported.
There are two processors and all 8 fan slots are populated.
Can you give me some guidance as to what the issue may be?
The BIOS firmware level is P71-09/08/2013 and is probably pretty far out of date but I'm not ruling out MB issue.
Thanks for any help
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Casey WeaverManaged Services Windows Engineer IIICommented:
The first recommendation would be to update the server with an HP SPP (Service Pack for ProLiant). It could be a sensor that has lost calibration or an iLO firmware issue. Beyond that, it will most likely be a mainboard problem. You'll need an active HP maintenance contract on the server to get access to the SPP.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Backplane fault
andyalderSaggar maker's framemakerCommented:
Unfortunately there isn't a fan backplane they plug directly into the motherboard. The fans are hot-plug if you can get the server lid off without pulling all the cables out and it will run ok but loudly with a fan missing.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Backplane fault on the motherboard!
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Motherboard duff!
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Server Hardware

From novice to tech pro — start learning today.