P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature
03-17-2011
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P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature what the heck do I do with this lol.
the person that checked it told me I needed a new thermostat that would cost about 13 dollars. replace it and thats all.
is this right? do i need anything other than a new thermostat to fix my problem??
where can i buy this part?
where am i? no just kidding. i need help though. thanks =]
the person that checked it told me I needed a new thermostat that would cost about 13 dollars. replace it and thats all.
is this right? do i need anything other than a new thermostat to fix my problem??
where can i buy this part?
where am i? no just kidding. i need help though. thanks =]
03-17-2011
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Re: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Tempera
That's what I'd do. If coolant temps were being regulated low, most likely means the thing is stuck open.
Buy the thermostat and some coolant (I use Prestone 50/50 mix because I'm lazy and don't wanna mix it myself) and swap the thing..
Well, drain coolant, remove old thermostat, pop in new one, reconnect everything, refill coolant, bleed coolant, call it a day. Pretty easy and straightforward.
Buy the thermostat and some coolant (I use Prestone 50/50 mix because I'm lazy and don't wanna mix it myself) and swap the thing..
Well, drain coolant, remove old thermostat, pop in new one, reconnect everything, refill coolant, bleed coolant, call it a day. Pretty easy and straightforward.
03-17-2011
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i only drove the car 4 hrs ago and they checked it with like 1 min of the car being on that has nothing to do with it right?
03-17-2011
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if the engine light came on, then the problem happened sometime already and is real. ive actually never heard of anyone getting that code, but it does sound like a bad thermo. just grab one from honda dealer, they work the best.
03-18-2011
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haha im the first. yay how awesome. :sarcasm
anyways the ones they sell at autozone are 13 bucks. how much at honda dealer?
btw i looked around and there is no diy on how to change that thing. :O it looks simple but i still dont want to mess anything up. any suggestions?
anyways the ones they sell at autozone are 13 bucks. how much at honda dealer?
btw i looked around and there is no diy on how to change that thing. :O it looks simple but i still dont want to mess anything up. any suggestions?
03-18-2011
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Rep Power: 788 Re: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Tempera
open radiator cap and remove it, then look at the bottom of the radiator for a drain ****. undo that and let some coolant drain out, maybe 1/2 total just so there is no coolant in the thermostat. unbolt the thermo case and remove the old one. install the new one in the same order. do not use gasket sealer, just the oem rubber gasket. it should only go back one way. rebolt the housing, then fill the coolant back in. start car with cap off and warm to normal temp by revving to 3k rpms if needed. turn fan to full and temp to hot, wait for air bubbles to come out from radiator and keep adding coolant til it stays full and no more bubbles come out.
03-18-2011
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Thanks gearbox. Can I drain the whole radiator cuz Idk what's in there :P like the mixture and all. Is that a problem or can I just drain the whole coolant instead of just half?
How much are the thermostats at Honda?
How much are the thermostats at Honda?
03-18-2011
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yeah if you want drain the whole thing. i got my honda thermo on ebay around $20 shipped i think. its worth it for something that lasts maybe 10yrs+ and actually works.
04-14-2011
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apperantly the guy that had this car decided it did not need a thermostat!! Grrr
i looked in there finally. and it was missing the thermostat! goodness... well is there anything wrong with that? something i should do or check?
i looked in there finally. and it was missing the thermostat! goodness... well is there anything wrong with that? something i should do or check?
04-14-2011
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well long term use without thermostat in cool weather means the engine does not reach operating temp very fast, if at all. that means the ecu stays in "warmup mode" which basically means running pig rich all the time. this can cause all sorts of problems the least being fouled oxygen sensors and cat converter, the worst being the engine is filled with carbon deposits. you do not want the engine running rich any longer than it absolutely has to (no more than a few minutes normally). and its hard to see what the damage is. i would recommend at least replacing the oxygen sensors. on a civic like this, the radiator is almost too much for the engine and on cold days without a thermostat, there is no way the engine will stay warm without a thermostat to block coolant flow to the radiator.
04-16-2011
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damn. well if wouldnt the check engine light be on if i needed to replace any sensors??
04-16-2011
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well technically yeah the light may come on, but thats usually not until the sensor is completely dead. it can still be very old or used up and not trigger the engine light, but it wont work as well as a new one. chances are everythings okay. that was a worst case scenerio i gave.
04-17-2011
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Thanks again gearbox. I think I'll hold off since I'm feeling in need if new tires.... which means rims finally.
11-29-2016
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Re: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Tempera
02 Ex Coupe 155k. Code P0128. Changed Genuine Honda Thermostat, ECT sensor, Electronic Load Detector, Costco Battery,. Car runs fine. Temperature reaches to normal 45% in about 1 mile of driving. 5 volts and continuity to ground at each incoming plug wire. What to do. Help please.
11-29-2016
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Re: P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Tempera
Yes, there is a software update for the P0128, that should be done first. (Bulletin 03-002)
Check different dealers for a price, we are only getting about half of that number for a single software upload into one control unit.
There is no way to tell if the car already has the newer software, we MUST connect the little electronic gizmo to the car to find out.
Use a factory thermostat with a new seal.
Don't bother with cheapos, they have a high fail rate and tend to open at a lower temp than what it should.
An inaccurate temp sensor can cause it too.
But...
The code set because the computer is seeing a coolant temperature that is lower than it thinks it should.
The software update (reflash) changes what the computer thinks it should see.
CopyPaste from the Honda site, Service News Oct. 03:
The problem may not be the coolant
thermostat, but a deficiency in the ECM/PCM
software. Under certain driving conditions after
a cold start, the ECM/PCM can miscalculate how
fast the engine coolant temperature rises and set
DTC P0128 or P1486.
If the heater and temperature gauge work OK,
don’t replace the thermostat for this DTC; it
doesn’t give a lasting repair.
HTH
Check different dealers for a price, we are only getting about half of that number for a single software upload into one control unit.
There is no way to tell if the car already has the newer software, we MUST connect the little electronic gizmo to the car to find out.
Use a factory thermostat with a new seal.
Don't bother with cheapos, they have a high fail rate and tend to open at a lower temp than what it should.
An inaccurate temp sensor can cause it too.
But...
The code set because the computer is seeing a coolant temperature that is lower than it thinks it should.
The software update (reflash) changes what the computer thinks it should see.
CopyPaste from the Honda site, Service News Oct. 03:
The problem may not be the coolant
thermostat, but a deficiency in the ECM/PCM
software. Under certain driving conditions after
a cold start, the ECM/PCM can miscalculate how
fast the engine coolant temperature rises and set
DTC P0128 or P1486.
If the heater and temperature gauge work OK,
don’t replace the thermostat for this DTC; it
doesn’t give a lasting repair.
HTH
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