Hello Everyone,

I just ran my OBDII scanner on my 2005 4cyl Honda Accord and it showed a P0128 code. I believe it is a thermostat issue. On my Auto X Ray device, I can see live data and it shows the coolant temperature rising pretty quickly to 177-181F and remains that way while I am driving. My question is, could it be the thermostat? Even though it reaches that the required temp rather quickly and could it fail with only 40,000 miles on it? Sensors? but the ECM is getting the proper coolant temp. sent to it.....I am confused. Any suggestions?

Thanks in advance!

 

There's also a temperature sensor in the lower tank of the radiator. Used to be a fan switch, but starting in 2005 or 2006 that became a sensor for the ECU. Maybe THAT one is doing something flaky?

I agree if your temperature reading comes up nicely & stays stable, then your thermostat seems to be OK.

 

is this code for the temperature sensor also?

 

That code just says "cooling system malfunction". I suspect it can be triggered by a combination of sensors whose readings don't make sense when taken together.