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p0128 coolant thermostat error code

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Old 04-30-2015
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p0128 coolant thermostat error code

I got a malfunction lamp come on this afternoon, so took it to pepboys to pull the code off. And it was

"p0128 coolant thermostat (coolant thermostat below thermostat regulating temperature) (x2)"

At least that's what the girl who did it wrote on my slip.

how should I proceed here? It seems to me there are more than one thermostat on civic?

What will be the cheapest way to fix this? I'm not very mechanically inclined. (can't properly unscrew and screw stuff without losing the parts)

What's a proper charge for the labor for this type of repairs, if I buy the parts online?

how do I know what parts to buy?

Thanks in advance for any info.
Old 04-30-2015
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Re: p0128 coolant thermostat error code

Get a FACTORY thermostat set, it comes with the correct gasket and is reliable, high quality parts that will probably last another 14 years easily. It's like $33 MSRP. And a gallon of coolant, another $20 or so. (Many dealers use their own pricing structure instead of MSRP, so prices may be significantly higher.)

Labor $$ at a shop I cannot answer. Maybe an hours worth of labor?
Many shops will not install customer supplied parts. Ask first.

Real world driveway time to change out the thermostat (only 2 bolts but there is a mess of antifreeze) then refill and burp the cooling system... Plus cleanup time and proper disposal of the old fluid.. Maybe an hour.


If the code returns after installing a factory thermostat correctly, then there is a software update that may address the code. There is a service bulletin about it, you would need to see your Honda dealer (or a super well equipped Honda specialist) for software update.

Take your pick as to which route you would like to try first: Software, or throwing parts at it.
Old 05-01-2015
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Re: p0128 coolant thermostat error code

Ok Thank you. I'll call honda and see if there's a charge for software update and call around to find a good labor price if it needs new parts
Old 05-01-2015
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Re: p0128 coolant thermostat error code

I guess I should have mentioned, if your temp gauge is running lower than usual that may be a good clue the thermostat is sticking open.


If you have a scanner that will read live engine data, you can watch your warmup time and operating temperatures. Sometimes you can spot a bad thermostat this way.
A flaky temp sensor could do similar things too.


Yes there should be a charge for software updates, but each dealer may have a different price. There is no set price as far as I know.
Old 05-03-2015
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Re: p0128 coolant thermostat error code

Ok Thanks. I fixed it. here's what happened. And it's a doozer.

Long story short, I had the dealer run a diagnostic for 100 bucks, bought the thermostat and coolant for 60 bucks, and went to a guy who replaced it for 40 bucks.

Here's the thermostat he removed on top of the bag for the right factory thermostat.


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He told me the previous owner whoever that was, (I got this at a whole sale seller who bought it at an auction), removed the actual thermostat part of the assembly. And he said people do this when the car overheats.

So he suggested replacing it to remove the check engine light message, and told me to drive it around to see if it overheats.

Which I did. Today I spent 50 minutes each way on freeway to travel to and from modesto. And here're the gauge readings when I got to and from Modesto.


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That's after traveling at 65 miph for 50 minutes or so and I was parked when i took the picture of the temp.

It doesn't seem to overheat. Am I good to go? Gauge remained in that position the entire time (once it got there from being cold) and didn't fluctuate at all.

I ask because, (this is the second doozer...) the coolant was green not blue like the honda one. (but not red though like the one that causes head gasket problems)

So the questions are...

1. Does the green coolant cause the head gasket problem also?

2. It seems like there is no permanent damage to the car?

3. Should I do a coolant flush and replace the entire coolant with honda spec one?

Also a bonus question. I'm actually pondering selling this car. I already spent over 450 on this car since I bought it on repairs over the last month.

On a good side, it has many positives,

- all the recall repairs have been finished today,

- factory tinted rear side windows/rear windshield,

-17 inch rims with two new tires and two good rear tires,

-automatic tranny that seems to be ok, (though it seems a little erratic when I accelerate once in a while, it revs up to 4000 or so before shifting, can't figure out what causes it),

-and the inside is practically brand new. One more positive is what one mechanic said I have some booster which i can't recall... Which brings me to my last question.

4. What's this muffler booster (?) called?

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Something low some booster or something... That's another positive thing about the car, it makes low muffler sounds that's not too loud but smooth.

Thanks for the info in advance.
Old 05-03-2015
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Re: p0128 coolant thermostat error code

Originally Posted by bo_red

He told me the previous owner whoever that was, (I got this at a whole sale seller who bought it at an auction), removed the actual thermostat part of the assembly. And he said people do this when the car overheats.
True, there's a reason someone did this.

Probably needs a head gasket.... Time will tell.
(There could be several other reasons but head gasket is very common.)


And here're the gauge readings
Inconclusive.
The gauge won't show anything until it loses enough antifreeze to overheat.

With a blown head gasket, this engine will slowly push coolant out of the radiator and overfill the reservoir while you drive, eventually overfilling or overflowing the reservoir bottle. This process starts out extremely slowly. Some people only notice an issue (overheat or just hot antifreeze smell, or maybe a few drips) after a trip of several hundred miles. Some don't notice anything until there is a catastrophic event.


You drove it 65 miles....See if the reservoir is now much higher than you left it, and see if the radiator is now low.

It doesn't seem to overheat. Am I good to go?
You have not yet found the real problem.
I ask because, (this is the second doozer...) the coolant was green not blue like the honda one. (but not red though like the one that causes head gasket problems)

So the questions are...

1. Does the green coolant cause the head gasket problem also?
Red? Haha, coolant color or type is not the cause of head gasket problems here.

2. It seems like there is no permanent damage to the car?
You gotta figure out the real reason someone gutted the thermostat. (The real problem with the car, not that the seller was motivated to be cheap.)
3. Should I do a coolant flush and replace the entire coolant with honda spec one?
That won't fix the problem..

Also a bonus question. I'm actually pondering selling this car. I already spent over 450 on this car since I bought it on repairs over the last month.
There is always a reason a used car is for sale. The reasons may vary widely but there is always a reason.


You bought a used car that needs work, work that you apparently are not able to do yourself, therefore you pay.
It's rare that a used car truly needs nothing in the way of repairs or maintenance, although some people will drive them in a state of neglect (or broken) anyway, drive it til it is ready for the junkyard.

Even brand new cars can have problems, that's why they come with a warranty.



-automatic tranny that seems to be ok, (though it seems a little erratic when I accelerate once in a while, it revs up to 4000 or so before shifting, can't figure out what causes it),
Floor the gas pedal from a dead stop and leave it on the floor, see how high the RPMs go before it shifts to 2nd gear. It should go to redline before it shifts.

The further you push the gas pedal down, the higher the shift points.



I have some booster which i can't recall..
Amplifier for the speakers?

4. What's this muffler booster (?) called?
A non-factory muffler that someone hung under there. If you like the sound, leave it alone.


HTH

Last edited by ezone; 05-03-2015 at 04:41 PM.
Old 05-03-2015
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Re: p0128 coolant thermostat error code

Thank you again ezone. I'll have to spend next week and see if the coolant overflow happens.
Old 05-03-2015
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Re: p0128 coolant thermostat error code

Just came back from a hour long drive and the coolant reservoir seems to be empty with no excess coolant in it. I think it's a good sign?
Old 05-03-2015
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Re: p0128 coolant thermostat error code

When your car reaches operating temperature the coolant heats up expands and flows into the reservoir. When the engine cools the coolant in the reservoir flows back into the block/engine. After an hour long drive your reservoir should be at it's max.

If your having head gasket issues when the engine is cold the reservoir will remain full to overflowing and when you remove the rad cap the radiator will be low. Don't remove the rad cap until the engine is cold...ever.
Old 05-03-2015
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Re: p0128 coolant thermostat error code

Originally Posted by bo_red
Just came back from a hour long drive and the coolant reservoir seems to be empty with no excess coolant in it. I think it's a good sign?
It should never be empty.

The radiator needs to be completely filled to the very top with all the air bled out, and the reservoir needs to be filled to the MAX line (or it may say full) molded into the side of the bottle. (I prefer to begin at the max level, the coolant evaporates slowly over time and this allows for more time between refills.)

That's a starting point.
After a couple of warmup and cooldown cycles top off the reservoir to the MAX or FULL LINE again. Now when you drive it should stabilize and return to the same level in the reservoir when the engine is cooled off. (Levels will rise and fall as engine temperature changes, as Stock99 noted)

See what happens from there on a daily basis.





Don't remove the rad cap until the engine is cold...ever.
Let the trained professionals open it while hot
Old 05-04-2015
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Re: p0128 coolant thermostat error code

Ok. ezone and stock99. thank you,. I'll check the radiator and the coolant level tomorrow morning.

Can I top it off with water? I don't have any green coolant, but have the honda spec coolant which is blue.
Old 05-04-2015
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Re: p0128 coolant thermostat error code

, but have the honda spec coolant which is blue.
Use this, not water.
Do not add water to Honda Type2 coolant, it says right on the jug 'do not add water'.
Old 05-04-2015
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Re: p0128 coolant thermostat error code

Originally Posted by ezone
Use this, not water.
Do not add water to Honda Type2 coolant, it says right on the jug 'do not add water'.
But the coolant in the car right now is green. Is it ok to mix blue honda coolant to green coolant in the radiator right now?
Old 05-04-2015
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Re: p0128 coolant thermostat error code

Originally Posted by bo_red
Is it ok to mix
Yes.
Old 05-04-2015
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Re: p0128 coolant thermostat error code

Ok Thank you.
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