P0128 Coolant Temp Below Thermostat Regulating Temp

P0128 Coolant Temp Below Thermostat Regulating Temp

all right we’re working on a 2001 Honda
Accord today and it came in for a check
engine light I hooked my little code
reader up to it is what I used to just
read and clear most engine lights that
come through the door this is a nice
little tool for me but I have I’ll leave
a link below in the video description
where you can buy these on Amazon pretty
cheap but I went ahead and pulled the
codes on this one we had a p0128 and
what’s that that is for is coolant
system performance typically when that
happens usually what that means is you
got a stuck thermostat or something
along those lines basically what the
computer does to set this code is it’s
monitoring how long the engine has been
running as to how hot the coolant has
got so if it takes too long to heat up
its gonna set this p0128
so one other thing I’m gonna be able to
do I’m gonna do before I thought that
I’m steadiness is I’m just gonna make
sure that the coolant temp is reading
properly and I’ll check that on cold
motor and a hot motor you will need a
scan tool to read data in order to be
able to do that this little one here
doesn’t or if you don’t have access to a
scan tool that does read data then I
would typically recommend just replacing
the thermostat clearing the codes
they’re cheap enough pretty easy to do
so and I’ll show you in this video later
on a little bit where that thermostat is
in relationship to the motor so if you
want to attempt to try and replace out
yourself you’ll be able to also another
thing to know is I actually did a little
research on this here and it appears as
though there is a service bulletin the
service bulletins for the 2001 Honda
Accord for the PCM actually being there
looked after replacing them so for this
actual this act this particular code
TSB says you can get it to focus here ya
go comes on with a people P0128 symptoms
cooling system malfunction.
replaced ECM p0128 and this is
for it’s only for 2001 accord l4 see you
affected vehicles but yeah and these are
part numbers the current part number and
the replacement part number so basically
they want you to access the computer and
check the part number on it right here
basically and you can see it’s right
behind the center console in the very
middle they want you to pull it out and
check that part number and if the part
number has not been updated to they want
you to update it I’ve been dealing with
these p01 2/8 for some time though and
I’ve never run across any circumstances
where the computer needed to be updated
from the old part number to a different
part network but I just wanted to throw
it out there because I did find the
service bulletins on this Honda I will leave some valuable
diagnostic information in the video
description below
that I pulled off identified it’d some
other research to online so be sure to
check down there along with a link to
that little handy scan tool. Its a
time saver
alright so a couple checks you’re gonna
want to make before you go ahead and
replace that thermostat is just make
sure your overflow bottle here is full
and also make sure the radiator is
full make sure there’s no pressure
first it’s not hot going pop cap open
and you know make sure your is pulling
here cuz if it’s low then cause you
could possibly have a leak and that
could be causing the p0128
cooling system malfunction on these
Honda’s the thermostat is right down
here not very good shot let me let me go
grab my flashlight over here and I’ll
show you where that thermostat and where
the coolant temp sensor is on these
110 sensors do go bad as well
long ago thermostats but right down here
you see right there there’s a thermostat
this 2 10 millimeter bolt to hold it
there’s a coolant temp sensor on top of
it there’s also another coolant temp
sensor on this side but hope this video
was helpful
if it was be sure to hit the thumbs up
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you guys watching Flate Rate Mechanic till next

9 Replies to “P0128 Coolant Temp Below Thermostat Regulating Temp”

  1. Hello, i have a 2005 Chevy Aveo. I bought this car a few months ago, but the check enginev light was coming on and off for " cam-shaft position sense" low circuit 1. Car drove fine for awhile. I stalled outna few days ago. I read it could be the cam shaft position sensorn. My brother norice the coolant around the thermostat housing when i had my hood open. I figure knock out 2 birds with one stone. I got both replaced. Thermostat housing and cam shaft position sensor. I drove the car around for 2 days and on my way into work the check engine light comes on, for p0128 coolant below thermostat. My mechanic did ask me to grab orange coolant when going to pick my car up at his house. I told him i had 50/50 in my trunk. Could this be the problem? Or js it stuck thermostat? Or is if coolant thermostat sensor?

  2. My 2012 subaru outback got this code the very first winter. It was brand new. I took the day off and went to the subaru dealer. They said, "mister graham, we reset the code and there is nothing wrong with your car". I said thank you and left. The second time was the same winter and so I took it back to the dealership and they said, "mister graham, we could find nothing wrong with your car. and I got into a fucking yelling match with this dick over that because I could see the writing on the wall. those cock suckers are not in the business of fixing cars. They sell them and they dont give a flying fuck about anyone, even their own god damn fucking customers. I gave up on the dealership, otherwise, i would have been driving 200 miles out of my way every time the fucking engine light would come on. I've had this car for almost 7 years and every god damn winter when it gets just below 20°F, I start the car and about 5 minutes later, BAM! the fucking light comes on and I know what it is, but the fucking dashboard lights up, kicks me out of cruise control, giving me only a slight heart attack and I stop the car and pull out my trusty code reader and its always the fucking same, P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature). why? because its fucking cold outside. Its a fucking NUISANCE and if I could program it out, I would. to me, it makes the car a fucking piece of SHIT!

  3. My mom's car will read p0128 every once in awhile but I just turn it off because the thermostat has been replaced. Don't know what keeps causing it to come on.

  4. MY VW Amarok has had a cooling system issue recently where it seemed the water temp was colder than it should be. While driving the car, the temp would be around 84 deg, but drop down to 50deg C. Then sometimes go up to 93-96, but quickly back down. I have had the thermostat changed, and while running the first time, the temp steadily went up to 94deg C and was up and down around that temp, but when idling my car for a while, the temp gauge drops down to 45deg C, and while idling, it stays around this low temp. Is that normal for the temp to be that low at idle?

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