P0128 Code

solidconceptgroup

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Looking for some opinions with this issue I'm having, I replaced my thermostat with a spoon t-stat, everything was good until two days after the install. The car kicked back an engine code reading P0128, I took it back to the tech who installed it, we ran tests and the t-stat is working, cooling fans are working, engine temps are slightly cooler and have not gone up what so ever, even in traffic. I called Hondata and was advised to remove the t-stat since racing t-stat cause more engine stress and could cause the ecu to bug out since its opening sooner?
Regardless I didn't take it out, I disabled the code and re-flashed and since then car has ran perfect with no code, I spoke with Spoon they replaced the T-stat for me, and I recently installed the new one. Bare in mind I didn't re-flash the ecu. I've taken the car on countless canyon runs, and two track days to SOW no heating issues, nor did the temps go up on track.

Two days ago, I figured I would enable the sensor again and reflash, well guess what the error code came back up! I had another tech inspect it and he suggested I should do a hard reset on ECU to remove the code, I told him we had done that the first time when I had brought back to the tech, he said it might be the t-stat (I don't think so).

I don't know what it can be? t-stat is opening and closing, fans are running, fresh coolant, I've tracked it and no heating issues, reached out to people who are running the spoon tstat and they've had no issues what's so ever... any advice?
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kefi

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The P0128 code means the coolant isn't reaching the temp it's supposed to. This code is exactly what you should expect because it's telling you the thermostat is basically doing it's job - the coolant is being let into the engine early and it's not reaching the normal OEM temperature.

Personally I think it's snake oil and potentially even dangerous since the metals of the engine may not be in the correct tolerance due to expansion, or lack thereof, but it's your car.
 
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tinyman392

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Well you describe the car as temps rising, but remaining under regulating temperature. P0128 is specifically saying that the motor isnā€™t hitting engine regulating temperature. The P0128 code isnā€™t for being too hot, itā€˜s for being too cold. I think P0128 can also come up if the engine doesnā€™t warm up fast enough too.

Edit: damn, ninjaā€™d.
 

Jpierro79

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Lower thermostat temps donā€™t reduce total temps ever. The cooling capacity remains the same as at 174 degrees itā€™s far lower than most cars. Most are at least 185 or higher. I had a 175 in my zl1 and I wouldnt dare go colder cause carbon build up Is an issue from not have it enough combustion temps. As Kefi says snake oil. Especially on a car that has plastic intake manifolds that donā€™t absorb heat. It used to work in old school cars cause the intake manifold channeled coolant. With direct injection engine temps are much more crucial to proper combustion. Cooling more equals colder cylinder walls making less efficiency and actually less power in many scenarios. To make power you want the cooling to come from fuels in combustion chamber and if thereā€™s not enough heat you do not cause enough fuel vaporization on richer mixtures and lose power.

Water meth does not create as much power till the engine is warm for a reason.

So either turn off the code cause another thermostat will do the exact same thing or put the o thermostat in. Also too much flow can actually reduce total cooling capacity. Donā€™t have to believe me feel free to look up combustion efficiency and cooling effeciency. Running a non restrictive cooling will actually cause poor temperature cooling. You canā€™t have the coolant go through the radiator too fast. A lot of people think removing the thermostat is better l. Itā€™s not at all.
 


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solidconceptgroup

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The more I read the response the more I'm leaning towards removing it tbh! I want to keep tracking the car and if this may contribute to more severe issues down line, I'd rather take it out now, its a quick fix. I'm planning on putting a radiator by the end of the month, might as well pull it and save the headache down the line...

Thanks again fellas for the feedback, much appreciated!!!
 

DRUSA

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Every response in here has been pretty much dead on point, hats off to all those commenting. Go back to stock. You are freaking out the PCM, it is referencing time it takes to reach operation temps etc, it thinks the thermostat is stuck open.
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