# Coolant question (Error code P0128)



## moneyjohn (Feb 29, 2012)

Hello folks,

This question is for 2006 Nissan Sentra 1.8S Limited Edition.

"service engine soon' light is up since sunday and the error code is P0128 (according to Autozone). The guy suggested DW, before you go to your mechanic, check coolant level and top it up, drive for at least 30 miles and then see if the light is still up. He was in hurry so could not help her more.

As far as I gathered from google and the manual, there is a coolant tank under the hood on left hand side (me facing the engine) and I check how much is in there. If its below 'minimum' level, I top it up to 'Max' level. It also mentions that if the tank is empty, check the level in the radiator. I got lost there. How do I check the level in the radiator?

I don't have car with me so not too sure what color is the antifreeze/coolant. Any suggestions with the brand are welcome.

Thanks a ton in advance.


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## jdg (Aug 27, 2009)

That code is for coolant temp below temperature...as in your thermostat is sticking open.
But, depending where you're at, it's cold out there. I say let it ride...
If the engine is making some heat and the heater inside the car is working, don't worry about it.
Now, if you heater isn't working, and your engine temp gauge isn't reading anything or is reading REALLY, well, now you might have a problem...low coolant...as in...coolant not touching the sensor therefore it's thinking it's not getting warmed up at all when in reality it's about to overheat.

How to check the coolant in the radiator? Really? You don't have an owners manual for that?


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## moneyjohn (Feb 29, 2012)

Thanks jdg,

I live close to NYC and its been little colder here lately, about 20F or so. Heater inside the car is working fine, no problem. Engine temp gauge isn't showing anything abnormal, its half way through as usual. I will check tomorrow morning when the car cools down enough.

I googled more about coolant and the radiator question and found that its as easy as opening the radiator cap and checking it there. This is my first car and I don't know anything about the cars (but I can tell inside out about your meds) so this question must have sounded like I am trolling but trust me, it was honest question. It is too simple to be in the owner's manual (i did not find it, unless I missed it)

In case, if the coolant level is low, any suggestions for the brand of coolant I should be using? I read that 50/50 is ready-to-use, so I am just going to go with it, even if its little expensive.

Thanks again in advance.


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## jdg (Aug 27, 2009)

moneyjohn said:


> I live close to NYC and its been little colder here lately, about 20F or so.


20F isn't cold, but it's getting there.



> Heater inside the car is working fine, no problem. Engine temp gauge isn't showing anything abnormal, its half way through as usual. I will check tomorrow morning when the car cools down enough.


Then you likely have _enough_ coolant in there. If you were running short, there probably wouldn't be enough water to get up into the heater core AND you'd be overheating the engine without knowing it.



> I googled more about coolant and the radiator question and found that its as easy as opening the radiator cap and checking it there.


No it's not. You have to check the overflow tank.



> This is my first car and I don't know anything about the cars


Goes without saying...also goes WITH saying that Google (or any search engine or friends) is good.



> (but I can tell inside out about your meds)


Sounds like a college level statement.
Must've taken CSR101.



> so this question must have sounded like I am trolling but trust me, it was honest question. It is too simple to be in the owner's manual (i did not find it, unless I missed it)


Just downloaded a copy, found the answer straight away.



> In case, if the coolant level is low, any suggestions for the brand of coolant I should be using?


Brand name, Prestone, etc. None of that "store brand" crap (e.g. Walmart, Autozone, whatever).



> I read that 50/50 is ready-to-use, so I am just going to go with it, even if its little expensive.


Ya, easy to use and expensive, especially if you are unable to mix two products together (e.g. coolant and water) in relatively equal (in this equal equal isn't the best) quantities....so baking cookies or cooking anything is out of the question...


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## moneyjohn (Feb 29, 2012)

Thanks again for taking time to reply.

It will be great if you could point me to the page where it talks about the radiator thing so that I understand it once and for all, instead of sounding stupid.


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## jdg (Aug 27, 2009)

Really?

You are unable to find the "Table of Contents" in the 2006 Nissan Sentra Owners Manual?

Really?

You are unable to find words such as Radiator, Cooling, Coolant, and Maintenance?

Really?

Let me google that for you


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