i had a hydraulic overheat on my last flight and it is now saved for future flights. any inputs on what caused it, and how to get ready of it.

i had the same problem and resetting the error in the failures menu of the FMC didnt switch off the error lights.you can load an other panel state to get rid of this, don´t know a better solution in the FCOMv2 at page 13.10.1 you find a description of the lights

Look at your fuel temp. If that's pegged all the way to the right the panel state is corrupt.

If you were using a Custom Made Panel State and this failure is already in there then do not use it again or it will continue to come back again and again. Use one of the Default NGX Panel States and make a new Custom Panel State from that and then save it. As for why it happens: It can happen when your in the middle of a flight and the sim crashes to desktop and you return and resume where you left off at the time of the crash using FSUIPC Autosave. If it happens this way then go in and clear the failures that are active and resume your flight. The warning lights will still be there and the fuel temp will be off the charts but it is just cosmetic after you clear the failures and you will not have any difficulty landing. The other way this happens is from Pilot Error. Read the Quote below from RSR.

Gents- One user-habit that we would like to break is: "I see a fault/failure that I didn't set, therefor it must be a bug in PMDG's software." To correct the original poster: Overtemp lights don't "just happen." They are triggered by causes, nearly all of which you can avoid with just a little bit of system knowledge... It has been awhile since I posted this, so here goes: First: Open your FCOM Vol2 to HYDRAULICS Pg. 13.20.3: You will not here that it warns you that you must have at a minimum 1,675lbs of fuel in each main tank in order to provide sufficient cooling to the fuel-cooled heat exchangers. When we have investigated users having a problem with overtemps, this is the #1 "ooops... I didn't realize that" item that we see for this type of report. It is worth noting that warm fuel is a possible cause if you are down near the minimum fuel quantity- although this is highly unlikely- it IS possible that your fuel temperature is insufficient to provide the required amount of heat removal through the fuel/hydraulic heat exchanger, thus causing a reduction in your available hydraulic EMDP case cooling. Next: Open the INTRODUCTION document to page 121/122. Take a read through the facts listed here on regarding the hydraulic pumps- it is educational and will give you a better idea what you are seeing. Now- some background that your books don't cover: Every time you cycle an EMDP on, the pump's output fluid temperature is going to jump around 20-25 degrees. This temperature spike comes about due to all the high velocity parts that start spinning, plus the fact that when the pump is not moving you are not getting cold hydraulic fluid to the pump, so upon startup the temperature of the entire unit jumps. The cooling of the pump will take about 5 minutes if the pump is on, and about 30 minutes if it is off. This seems counter-intuitive, no? The reason is quite simple: When the pump is running, you are getting fresh, cold hydraulic fluid to the case for cooling, hence the temperature comes down more quickly. If the pump is static, there is no cool fluid flow, this it takes longer. Neat eh? Okay- so if you cycle the EMDP's off/on a bunch of times- you WILL get a fluid overheat. If you do this until the temperature cutout sensors trip- you will notice that the OVERHEAT lights will go out, but you still have to wait around for awhile before the pump will become active again. The reason for this is explained on page 122... But once again- some pretty cool (or hot) detail for you. Now- one other thing we have seen with some users: If you have a flight state that was created with a stored EMDP failure, stored EMDP overheat, or if the flight was saved after the EMDP had been cycled a few times- you have some latent heat that is being tracked by the simulation... Over time the chance of an EMPD OVERHEAT will become more remote because the pump will cool... If you get an OVERHEAT light after loading the simulation and none of the obvious causes appear to be the trigger- this might be your issue... Hope this helps you guys appreciate the details!