It's not just a diode - it is a VDZT2 series 5,6V Zener diode. It protects DDC bus (clock line) from electrostatic discharges and electrical surges, so it is absolutely necessary to prevent from further and more expensive-to-repair damages. There are plenty of replacements available, eg. CDZVT2T5-6B or CDZFHT2RA5.6B (both available in Farnell). Saying that the console will work fine without this protection is just asking for troubles - I ‘m really concerned how such an irresponsible advice from @tronicsfix could be marked as Solution?

The upper capacitor (marked with a curved arrow) is a 1uF/25V (ceramic, 10%, 0402), and the other one is 2.2uF/16V (ceramic, 10%, 0402).

CFV is a SOT-23 current-shunt monitor INA214AIDCKR: http://www.ti.com/lit/ds/sbos437j/sbos43... The other component is a 2A ferrite bead BLM18AG121SN1D: https://docs-emea.rs-online.com/webdocs/11b5/0900766b811b5866... If there is no schematics available it does not mean you can't recognise the parts.

This is a clear and 100% effective solution for all iMacs with 4SNS/1/40000000:TH00-9.000 problem after replacing a HDD: https://www.elvikom.pl/imac-21-5-27-blad-4sns-1-40000000-th00-9-000-po-wymianie-hdd-t50744.html#p192746 Please note that Macs Fan Control DOESN'T solve the problem because you still have an error in Apple Hardware Test! Macs Fan Control does only control fan speeds and has nothing to do with a HDD temperature sensor detection. My solution resolves all the issues after HDD replacing, like: - Mac OS runs very slow, - fans are running at the maximum speed, - kernel task is equal or above 100% in Activity Monitor, - AHT and ASD are reporting TH00 temperature sensor error.

This is a clear and 100% effective solution for all iMacs with 4SNS/1/40000000:TH00-9.000 problem after replacing a HDD: https://www.elvikom.pl/imac-21-5-27-blad-4sns-1-40000000-th00-9-000-po-wymianie-hdd-t50744.html#p192746 Please note that Macs Fan Control DOESN'T solve the problem because you still have an error in Apple Hardware Test! Macs Fan Control does only control fan speeds and has nothing to do with a HDD temperature sensor detection. My solution resolves all the issues after HDD replacing, like: - Mac OS runs very slow, - fans are running at the maximum speed, - kernel task is equal or above 100% in Activity Monitor, - AHT and ASD are reporting TH00 temperature sensor error.