Honda Civic 9th Gen Fan Club (2013)

[mua.881]

Aoa. Long post and a complex issue ahead.
I have a 9th gen Civic 2012 model 135k on the odometer.
My car has been heating up lately. Initially the mechanic changed the radiator cap but no use.
Then I observed that the car heated up only when the AC was turned off as the fans won't turn on on time.
Keep the AC turned on and the car would be all good (as fans are always on with AC). The moment you turn the AC off, heat indicator would show up within 10 minutes.
After getting electrical check up, we found out that the radiator temperature sensor (bank 2) was not working correctly. We changed that sensor, one after the other. Till date I have changed this sensor 4 times but the problem is still there. I visited Honda Township, they said there is no electronic fault and you only need to get your radiator serviced. I got it done the next day but no use. The issue is still there.
2 days ago I visited Zaheer Dynamic on Walton Road Lahore. He did a detailed electronic checkup and the detailed situation was as follows:
As there are 2 temperature sensors in the car. One is water temperature sensor (bank 1) and the other is radiator water temperature sensor (bank 2).
The bank 2 sensor controls the turning on/off of fans. The bank 1 sensor brings up the heat light if the car temperature is high.
The fans turn on when the temperature of bank 2 sensor reaches 96 degrees. But surprisingly, within 3 to 5 seconds after the fans turn on, the temperature of bank 2 sensor drops to 75 degrees and the fans go off. Now the temperature starts rising slowly again and once it reaches 96 the fans are turned on again.
However, the temperature on bank 1 sensor does not fall that much. It only drops to around 92-94 when the fans are turned off by bank 2 sensor. Now when the bank 2 sensor turns the fans on again, this temperature has already reached 98 and within 3 to 4 such cycles, the temperature on bank 1 sensor reaches 105+ degrees and the heat light comes on! Interestingly at this point, the bank 2 sensor still says that the temperature is at 80-82 (so the fans are not turned on) however the car is fully heated up by this time.
Now while we were doing all this check up, another 9th gen civic came to the workshop and we connected scanner with it to see standard readings. In that car, the fans turned on when the bank 2 temperature reached 96 and were turned off after like 10 seconds when the temperature had dropped to 87 (Temperature did not fall all the way to 75 degrees!!!!) Moreover, the bank 1 sensor never went beyond 98 degrees in that car. However my car's bank 1 sensor goes up to 104-105!!!
Now zaheer dynamic changed the bank 2 sensor almost 3 times and the bank 1 sensor once in that session but the result did not change. Then he concluded that it was some problem with the ECU that the current it was giving to the bank 2 sensor was not right, so the bank 2 sensor is not performing ok, hence the fans don't turn on when needed and the car heats up. He thinks may be it is some bad IC in the ECU which was causing this. But he did something to bypass that IC (without opening the ECU). I did not understand what he did although he tried to explain to me in technical terms. At that time all the above mentioned readings were improved. They did not match or come close to the exact readings of that other civic. But they improved. The bank 2 sensor dropped to 82-83 now but after like 10 seconds of the fans turning on (not 3-5 seconds). We did a test drive with the scanner attached and monitored the readings which seemed fine. But the test drive lasted only 15-20 min max. The car worked fine yesterday.
BUT TODAY IT HEATED UP AGAIN........
And now I seriously don't know what to do. I called Zaheer Dynamic and he said that now we'll have to open the ECU. I'm completely confused what to do now. Should I get the ECU opened or not.
I have tried everything suggested by everyone. Including Honda authorized workshop.
Anyone else has had that issue? Or can any experts help me?

[aziz.rehan]

Brother is the car reducing coolant?And the temperature sensors u used were they oem or not.And the radiator cap u put on what is pressure written on it compared to factory one.And is it oem/geniune.Maybe the fan motors have become inefficient over time.

[aziz.rehan]

@Xulfiqar sir ur help is needed here

[aziz.rehan]

Check automatic transmission for any noises and do compression test of engine before buying.Ask owner which grade oil has he used.Ask him about transmission fluid changes.Check it's suspension.Check electronic steering by turning it fully side to side.Get the body check from a professional if accidented or not.And check for repaints.Check panel gaps.Don,t trust anyone when buying a used car.

[mua.881]

Aziz bhai Thank you for response. The car reduces coolant only when heated up. Otherwise if I keep using it with AC on, that means no heating up and no reduction in coolant. The radiator cap is OEM and pressure is 1.1
However, all the sensors replaced were not OEM. Because Honda guys were of the view that there is no electrical fault.

[aziz.rehan]

Unplug the sensor and drive for a few days without ac if it doesn't heatup then it's definitely electrical fault.honda guys are fools

[aziz.rehan]

Does the car have two fans setup or single fan set up?did u check ur thermostat valve?

[Thinking]

brother get your thermostat valve replaced. its not working as intended. not letting water in and out as per intended temperature rating.

in case issue persists you can talk to me 03335120067. i dont think its that complex with reborn.

i used to suspect similar thing with my car that fans werent turning on (even though the car never heated up and worked perfectly fine AL HAMD U LILLAH). however in honda the fans are independant and they run as per the temperature and working u mentioned above.

however thermostat valve and water body ensure circulation of water between engine and radiator. these are mechanical things and might rust up and cause malfunction if coolant is replaced with water.

once you have confirmed that water body/water pump and thermostat valve are fine just pour in honda type 2 coolant. IN SHA ALLAH your car will be fine.

Also check for thermostat valve is simple. just put it in water and boil the water and you will see that it will open up at boiling temperature. try and ensure that your current thermostat valve or the one you replace should be for your car exact honda part number. better to procure them from honda 3s or 1s.

trouble shoot it step by step. done worry it will be resolved IN SHA ALLAH.

[mua.881]

the car has two fans setup. Plus I forgot to mention, the thermostat valve was also removed during all this exercise. Right now the car is without a thermostat valve since a few weeks.

[mua.881]

Thank you for your time. The thermostat valve of the car is removed since a few weeks.
I have not done anything with the water body right now. Will definitely call you up soon Thank you!

[aziz.rehan]

Check the fan for radiator if it's working or not by unplugging the temperature sensor.Check for blown fuses as well

[Thinking]

please put the thermostat valve back in. without it the water keeps flowing between radiator and engine and you are getting the temperature issue probably because of that. also one more thing to verify is that fans of your radiator and condensor are working at the intended speed consistently, get their motors verified.

[Abd008]

Have you checked the water circulating pump? it may have a intermittent free impeller or slipping fan drive belt

[mua.881]

I put the thermostat valve back yesterday but the car heated up again on its way back home

[mua.881]

It was checked by the mechanic and not found to be faulty

[Thinking]

brother than here is your simple answer. your thermostat valve is faulty and not letting the water circulation in the engine at the required temperature.

change it with oem recommended new thermostat valve and your car will be fine IN SHA ALLAH.

[mua.881]

No i didn't put back the old thermostat valve back. It's an OEM but no luck

[Thinking]

brother probably new one is not ok. please get it verified and than install back or another one. how much did it cost? can you share the pics of thermostat valve that u installed.

one other issue can be that ideally thermostat valve and fans of radiator and ac work in conjunction. also get your fans and their functionality verified along with thermostat valve.

[Fahad.Ayub]

if you believe fan operation are normal ,water pump is fine then check for leaks.
the 2 most prone areas are the thermostat housing and coolant lines for the throttle body (make sure they have hose clamps on them)

[irfanje.irfanje.1]

Hello experts, i want to change my 2016 rebirth horn, Is it require bumper removal or not to change horn ?? thanks