My Engine light is on with code "P0128" on my EX -- L4 - 2.3L 2254cc type F23A4 - MFI GAS SOHC.

I went and got a temperature sensor;



Where can I change this out on my engine?



Where the red circle is I only found this;



I did an ohm test on this switch and did not read anything, dead open, no resistance at all.

If you could point me in the right direction, I would very much appreciate that. Thank you.

 

P0128 is Cooling System Malfunction. It does not necessarily mean the ECT sensor is faulty. Did you check coolant levels, radiator fan, thermostat, etc.?

Regardless, ECT sensor is under the distributor. See attached image.

 

Thank you for the quick reply, I checked the coolant levels and everything else and it is ok.

Strange thing is on my engine there is nothing attached as shown on your picture it is closed off.



I forgot to write that I did a ohm test on the switch inside red circle and it did not measure anything.

 

1. The cooling fan switch is in the approximate area where you have the red circle. The fan switch is normally open (so, it should have no continuity or resistance when cold). When the coolant temperature is above 199 degrees F at that switch, then the switch contacts closes (where you would get continuity).

2. The image I previously attached shows both the gauge sender unit and the ECT sensor. Your car (a 2001) will not have the gauge sender unit; but, it will still have the ECT sensor under there. Look further underneath the distributor.

On the ’00 -02 4 cylinder Accords, the coolant temperature gauge and ECM/PCM are controlled by a single ECT (engine coolant temperature) sensor. The signal from the ECT sensor will go to the ECM/PCM; and then from the ECM/PCM to the temperature gauge for your 2001.

Previous models (98-99 4 cylinder Accords) had the gauge sender unit for the gauge, and the ECT sensor for the ECM/PCM.

 

That's strange - it should be visible in that photo. Maybe the angle is wrong & you can't see further back where the sensor is.

In this picture, the sensor is #17. #14 is the gauge sender which is not present in your car (shared drawing over a few different years/models).

 

Yes that is where it was hiding;



Now to the bad news...I changed it, disconnected the battery and connected it back up. Light did go out, but it came back on after about 2 days. I just did a oil change and they refilled the coolant therefor the fluids are correct level. Temperature of engine is below half on gauge inside the car. Not sure what else it could be.

 

The troubleshooting for that code is pretty simple.

1. Fill the cooling system (done)

2. Turn the key to the II position, but do not start the car. Make sure the a/c is turned off. Does the radiator fan turn on?

3. Test the thermostat. I'd recommend getting the OEM thermostat from the Honda dealership. Don't go with aftermarket thermostats on Hondas.

 

Radiator fan did not turn on.

 

P0128 is usually due to a faulty thermostat.