Engine overheat

I just took a picture of second possible "fan sensor" in my car below the exhaust manifold. What is it called? Could you point me to the link of this part? Thanks,
-Tim

Hi Ken,
Thank you for getting back to me. The fan is working but not trigger to run at when temperature is high; as such, I think it might be the fan sensor issue.

- I checked the 1st video: I don't see symptoms described in the video (coolant in engine). We have timing belt replaced in 2 years so gasket is supposed to be good.

- I reviewed 2nd video: it is very general. It also mentions about fan issue. It could be fan sensor.

The diagram does not include fan switch sensors. So, I am confused. What do you think?
Thanks,
-Tim

Hi Ken,

Thank you. I edited the diagram and added in text to wire. Could you confirm that is the sensor wire you want me to try?

As I mentioned in the initial report, if I removed the socket out from sensor as in 2nd attached picture, the fan ran. The wire to this socket is "light green"

(I hit wrong button)
. Here is attached edited diagram with 2 texts on "light green" wire: (1) and (2). Which one you want me to try?

I don't know if light green wire from my car (in previous picture) is (1) or (2). My best guess is that it is (1) as it is on engine block, far away from A/C unit.

Many thanks,
-Tim

Yes, once I removed the wire, the fan ran. This is the switch I planed to buy and replace:

https://www.amazon.com/gp/product/B000CB3EQO/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

Thank you so much for your suggestion.
-Tim

Ken, I have good and bad news.

I installed the new fan switch (from amazon order as above) and had OPD2 bluetooth readout to monitor temperature. Below was my findings:

1. Overheat issue was still not fixed.

2. As engine was running, the fan was kicked in when temperature reached 115C (above water boiling level). At that time, the temperature gauge already pointed to "H". As fan kicked in, temperature reduced down to 107C. Then, fan was switched off after that. As such temperature readout fluctuated a lot between 107 and 115.

3. If I turned off the engine (but still leave the key in the "ON" position), the fan stayed ON until temperature was below 100C (which was what we wanted).

From that experiment, the fan switch appears to work and fixes part of the problem. But something else interferes with the switch so that it is turned off at 107C. I fear that 2nd switch (picture posted on Sun 2/25) might need to be replaced but:
1. I don't know what it is called and how to find that part number.
2. I need to find another way to test if that switch is my problem.

From your posted diagram, there is also 2nd switch (AC high pressure switch). Is there anyway you can help narrow down to part number and its location for me?

Please let me know if you have any suggestions. Thanks,
-Tim

From the article: when the gasket fails it can do so in five different ways.

1. Allowing coolant into the engine oil
2. Allow coolant to leak outside of the engine
3. Mix combustion gasses into the cooling system (radiator)
4. Allow combustion to transfer between two cylinders
5. Allow engine oil to leak outside of the engine

I reviewed paper. I do not have equipment to check for air pressure. But, I don't think it is gasket because:
1. Check oil fill cap --> do not see "milky goo" as shown in step 1
2. Check oil stick --> do not indication of water. I did change engine oil after we first ran into this issue. I did not notice water in the oil either when I put used oil in the recycle container
3. I let engine run with radiator cap off to observe coolant flow --> do not see water bubbles as in step 3.

Thanks,
-Tim

Thanks. I will give it a try.
-Tim

KHLOW,
Thank you for your feedback. It seemed much easier for me to try it out. I observed hot steam from the cap when coolant was boiling. But I did not realize important of the cap to hold pressure in the radiator. I have ordered the part today and hope for the best. Thanks,
-Tim

Update from last message:
Changing the radiator cap did not solve the issue. I gave up and took the car to the shop. It turned out that rusted radiator is the source of the overheat issue. I changed the radiator fluid and flushed the radiator earlier but I could not get rid of the rusted color. It seemed that radiator was clogged due to rust.

That is a learning lesson for me. It cost $320.00 to fix. Thank you very much for suggestion.
-Tim