i changed the oil and radiator fluids in my 2005 toyota highlander and after about 2 hours, the check engine, vsc and trac off lights came on. used SAE 10w-40 instead of SAE 5w-30. is that the cause?

NO,did you leave something off

May I ask how you fix the problem? I have similar case from my Highlander 2007. After a dealer service to replace its oil, about 3 hour drive, then Check Engine and VSC lights on. Any idea?

check the gas cap for loosen or take off the battery positive for 30 sec to reset the syatem

you've a few options to make it easy go to auto zone and get a free diagnostic and tell me what code they get

I had this same problem. There is a hose that frequently gets disconnected when inspecting/changing the air filter and when disconnected causes this light to go on. If you can't figure it out, you might try Jiffy Lube or Midas as I have discussed with them a few times and they seem to be aware of it at most shops.

I am having same issues , but FYI with other cars like my Mopar I found that auto parts store parts will not work , I had to get the dealership gas cap , cam sensor and crank sensor so far to fix my problems in the past. So my question is what good are auto zone, Napa, and O'Reilly these days ? Even for a gas cap , go to the dealer, this sucks .