Hi guys I got 2002 lexus es300, 134k mileage. 2 days ago it was overheated when i stopped at the red light. Engine light came on. I went to the autozone, they checked and code P0117, P0118 came up. The said it is is the coolant temp sensor. I bought and replaced it but it is still overheated. I forgot to mention that both fans are not working too. Any helps ?

I think radiator is clean when i trained coolant out, it looks normal. When i unlcoked the cap, it released pressure sound, so assume it is good. But i really dont know if it is bad or good. Coolant level sometime it is low on overflow tank, sometime it is top of overflow tank. Is that normal?
i noticed there are 2 temperature sensor. One is on engine block, one is on the radiator. I changed the one on engine block but it did not fix the problem. Fans wont come on. Should i change the one on radiator? I dont know what function of those sensors?

In most automobiles the block engine temp sensor mostly controls fuel mixture based on engine temp, like when you first start it up in the morning for instance. Radiator temp sensor controls the fans.

And about the radiator cap, they’re $10 at lexuspartsnow.com or $20 on eBay w/free shipping and worth every cent if it helps keeps heads from warping with overheating problems. Replacing a 16yo radiator cap isn’t “throwing parts”, it’s good sense and can save huge bucks in the long run.

After you fix this overheating problem, keep a very close eye on water levels in your cooling system. Losing water might mean a warped head and a leaking head gasket.

Fans are finally working after i changed the sensor ( on the radiator, cost $105). But i also have to add more coolant to the engine ( like almost 1 gal). Look like my car is eating coolant. I got under the car, checked around, there is no sign of leaking coolant. Here is something new, after i changed sensor and added more coolant, i started up my car, a lot of smoke came out from tailpipe. Did i add too much coolant causing the problem?

Ooooo... This is not a good sign and just what I was speaking of earlier. You either have (hopefully) a blown head gasket... or a warped head along with it and that means m-o-n-e-y. Not to worry though, there are puh-lenty of used Toyota/Lexus heads out there that fit your motor in junkyards and shops, so don’t give it up. Besides, the job will give you a chance to change plugs and knock sensors if needed while you’re in there.

Good luck and let us know how it goes.

i did some researches online, and found a liquid seal that can fix a head gasket problem ( blue devil or bar leak). I dont know what to do if there was a bad cylinder head.
What else symptoms beside the smoke from tailpipe that telling you about bad head gasket ? Should i try the blue devil or bar leak instead ?