Had transmission on Lexus RX450h drained/refilled two weeks ago, as vehicle hit 100,000 miles by trusted mechanic (not dealer) .. that's usually the point that i change automatic transmission fluid, no matter what's been done before (we've only had the vehicle for 20,000 miles). Afterward, car ran fine around town.

Week later, travelling at 70 mph for 30 minutes ... "Hybrid System Overheat" error flashes on dashboard ... power is lost, car goes down to 40 mph. Smelled "oily smell" afterward ... but no dripping on pavement.

Get off the interstate, let it cool down, drive home and switch cars. Took it to Lexus dealer said "it all looks good, not sure what's going on"

Took it on interstate again on Saturday to test, and same thing happened -- 30 minutes at 70 mph "Hybrid System Overheat" ... made sure nothing is blocking the vents in the back seat of the Lexus, etc.

Never had this problem before. Could it be related to the transmission fluid service?

 

On older Toyota/Lexus hybrid this happens due to the battery pack getting too hot, generally caused by clogged cooling fans (back part of vehicle). I don't know if this message will pop up due to overheating transmission. Anyone know?

It would be good to get the transmission fluid level checked just to be sure it is very simple, see this video at about :55 seconds.

 

What is the condition/status/level of the inverter coolant?

Salim

 

https://www.toyotanation.com/threads...b-diy.1721403/

Talks about trans being overfilled

 

Seems difficult to do you'd have to pump in fluid then close the fill plug quickly before the excess drains. But good find and I like I said easy to check.

 

I too think the hybrid battery pack cooling duct work and fans are clogged with dust after 10 years. I think the rear seat and maybe part of the rear floor needs to be removed to access everything. If you have a filter for this ductwork, it needs to be cleaned or replaced too. I did this on my 2011 Lexus HS250h a few years ago and the battery cooling ductwork and fan were pretty dusty!

You need to find an indepedent hybrid shop to check it out and maybe clean them for you since it appears you are not a do it yourself repair person. There are many hybrid shops that have opened in the last several years, including a national chain. Using the usual internet searches you should be able to determine if there is one nearby.

 

You probably have a bad fan. Same thing happened to my 2010 about 6 months ago. I had all 3 fans replaced for $1600 at the dealer in Chicago area.

I’ve seen some videos online people replacing them.