My E7470 is also frequently forgetting about its TPM. It's is really quite annoying, especially when you have a meeting with a customer and want to turn on your PC and then have to get out the long BitLocker code to be able to start your own PC. Removing the batterie and RAM and re-inserting it helps, but you need to unscrew the back, so thats not very convenient.
Does anybody have a permanent solution? The DELL Support actually told me to post my question in the forum because they dont know of any.
I recently had this issue and was advised by Dell to open the system and pull the main battery connection then the CMOS battery connection. Then hit the power button to drain power from the main system board (make sure you do not have the AC adapter connected). After that, re-connect everything and power it back up. the TPM should be listed in device manager again.
So here we are June 2017 and still having issues with the E7470 (new out of the box)- TPM and Bitlocker. Latest BIOS was installed but rolled back. TPM driver is the latest. The current enterprise OS is 32-bit Windows 7 Ent. Was there ever a process/driver/firmware procedure developed that works with this OS? We can't let this laptop out without Bitlocker operational.
I agree it's June of 2017 and I too haven't seen anything to resolve this issue. My case is worse in that the systems don't even boot once the TPM quits working, the screen goes black, the hard drive light isn't blinking and nobody is home once the dell boot UEFI/BIOS logo goes away. You lucky folks are at least receiving the option to put in your recovery key. I can run Dell's own OEM diagnostic and pass it, other bootable drive diagnostics confirm that the drive is 100%. I can reinstall windows and get the device working again, but we don't have the resources to backup/reinstall computers every week. I believe there is something defective with a high percentage of the TPM's specifically on E7470's. We too have older models that worked great, including the E7250 and E7450 which also have a TPM 2.0, but apparently a better one. On those older models I had to downgrade the TPM to run Bitlocker on Windows 7. The E7470 allows you to run Bitlocker with either version of the TPM, but for me the result has been the same, rampant failure hours, days, or months after setting up their devices. We're running Windows 7 X64 Enterprise and BitLocker with a TPM validation profile that only checks step #11. So if anything our computers should be more likely to boot and less likely to challenge the user for a key. Instead we don't even get a prompt for the key, the OS flat out fails to boot on the same image that works great with TPM's from OptiPlex 9010's, Latitude E7250,7450, HP EliteDesk 800's, and various other models all with the same OS image and TPM validation profile. At this point the only remediation would seem to be to have Dell's warranty replace the motherboard. My issue is we have about 12 more of these units and frankly I'm afraid to deploy them.
I'd also like to point out that we've deployed 17 of these and 4 had bad TPM's which is a 24% failure rate.
Have tried all the steps mentioned , still no luck .
Though the TPM is visible in BIOS but not able to resume in Device manager.
I have had the TPM disappear twice on my E7470. Both times I had to take the cover off remove the m.2 Drive. Wait 10 seconds. Put the drive back in... and then presto the TPM comes back. I was running an old 1.1 version of the firmware... and i tried updating to 1.6 but it did not fix the problem.
Remove the m.2 Drive from the laptop. wait a minute... and replace it... Worked twice for me now.
I am having the same issue with my E7270...booting F2 looking is BIOS security and TPM setting is gone....booting again and check the same and it is there...then rebooting and it is gone...it is random available. Also tries the latest BIOS update 1.17, but still the issue.....will create case to replace the laptop. This one is useless now and I can't find a working proper solution.