My Z threw this code (Coolant Temperature Below Regulating Thermostat Temperature) about 3 weeks ago. I took it to the service department at Nissan, and they said it was the thermostat. They replaced it. Yesterday, my SES light came on again, and I went to have the code read again. It was the same code. My mods are the Motordyne Shockwave dual exhaust and AAM test pipes.

Anyone know what could be causing this to happen repeatedly?

 

I just threw the same code. My car is having the t-stat replaced as we speak.
wtf.

I was told by a local trusted mechanic that this would not affect performance,
however I could not get the light to remain off - so I ordered it replaced...

 

yeah, it came back on after i had the thermostat replaced. i don't know what's causing it.

 

Bad temperature sensors?

 

that was my only guess man.

you think there is there any way exhaust could cause this problem? my friend has been running the same setup longer than i have and has had no problem. i ran with it for a month without any SES light.

 

What is the actual code you're getting?

 

i believe it was this one.

http://www.ncttora.com/fsm/04-06-Tun...fe/cip0128.pdf

the coolant temperature gauge is showing that it's running normal.

 

The only way that I can see test pipes causing the problem is if you busted the temperature sensor or the harness connecting to it while installing the TPs.

The sensor is mounted on the pipe that runs across the back side of the engine. I believe you have to attack one of the bolts on the header/cat flanges to get it off from that area of the engine bay, correct?

Double check to make sure it's connected and looks okay. If it is, your car is still under warranty so I'd bring it back or at least call the dealer and ask them if they tested the sensor prior to deciding it was the thermostat.

 

cool, thanks for the advice. i'll probably put the car on a lift and have the sensor checked by one of my friends who is a mechanic. i called the service dept. today, and i'm supposed to bring the car in monday. they're usually pretty cool about mods on Zs, so i hope they don't try to throw my warranty out because of test pipes.

 

it might be impossible to determine if its broken/malfunctioning aside from
the code throwing. interesting to hear you had the light return... how quickly?
i just got my car back w a new t-stat installed and frankly my car feels
different (in a good way), and no code as yet.

 

it took one week before it came back on. there was no difference in performance.

 

and... not entirely to my surprise the code popped again even with the new
t-stat. at least you're not out $200.00 for the part/install as I assume you had
same performed under warranty.

anyone else have input on this? i assume i wasted the money to replace.
any info on how this could/might/will affect performance?

 

it may be bad sensors. i have no idea. i just drove my z on a 200 mile trip and had no problems. yeah, mine was under warranty the first time, but they may not cover it this time because my z has been modified; however, i'm going to make them prove that my exhaust is the cause if they blame it. i don't understand why it's messing up though. my z is garage kept, and i let it warm up for about 5-10 minutes before i drive it, and i let it idle for about 3 minutes before i turn it off.

 

mine is 80k miles, 2003, and only has exhaust/intake for all intensive
purposes. i am a bit sour about the expenditure, but it's frankly the
least of my fiscal mistakes of late. i have never heard of this issue
beyond your and my problem... par.

 

my Z has 47xxx miles, but i have the extended warranty. i don't know if the thermostat is covered under the powertrain warranty or not.

what exhaust do you have?

 

dc sports...

 

well that goes to show that it can't be the exhaust.

 

this site gives a good checklist:

http://www.obd-codes.com/p0128

 

now my z is starting to run cooler. the coolant temp needle is sitting between low and the halfway mark (about 1/4 the way up).

the dealership is probably going to blame it on the exhaust because i talked to the service advisor, and he said that the lack of back pressure may be causing the engine to not warm up as quickly. if this is true, i'm not worried about getting it fixed anyway because it's just a winter issue; however, i'm afraid it may be something else causing the problem since my z didn't warm all the way up tonight after driving on the highway.

 

i have a powerlab turbo setup..i took the car out for drift and drag this weekend. 68 degrees out side..perfect ran awsome all day..two days later i get the p0128 code..it was 34 degrees outside. however no performance loss and my temp gauge shows normal "a lil below half" i also have a mishimoto thermostat, hoses, fanshroud and radiator and still throwing this new code..