Throwing code P0128 -- 2003 3.2 L

**DMC-12** · 02-10-07 02:04 AM

Hey Gang...

Its been cold as hell here the past two weeks... and the Caddy just started throwing code P0128 -- "Coolant Thermostat Below Thermostat Regulating Temperature", during the past couple of days. Aka... its not getting up to 170 degrees.

I cleared the code yesterday... and it came back a day later on the way home tonight. My guess is the thermostat is screwed. BUT, I also have the HVAC cranked up to 90 degrees and at full blast...lol. So the interior gets nice and toasty with no probs.

After searching here on the forums, for info on this... I dont feel like being anal raped by the dealer for $600, with no lube... to replace a $12 stat.

Ideas & Suggestions are welcome. Do I just ride it out till it gets warmer out? Anyone know of any place in the Chicago area... that wont rape me $600 for a thermostat replacement?

Thanks in advance.

-JZ

**B0000rt** · 02-10-07 10:32 AM

I'm in the same situation, I don't think much can go wrong if you leave it how it is for another few months, the stat open and all.

I personally already have the stat w/ me, and I'm just waiting for the warmer weather. I believe you need a few more gaskets as you're going to have to take off the Intake Manifold to get at it. Lemme scan you the instructions.

Here you go:

**DMC-12** · 02-10-07 12:20 PM

Cool! Thanks for the info, B0000rt!

It 'sounds' easy in the instructions... but I bet its anything but. :-\

**Nels** · 02-10-07 02:14 PM

What's the milage on the cars? I had this code come up on several GM platforms at work. There are a few things that can cause the code to appear. 1) With Dex-Cool coolant we found alot of slag in the cooling system, which builds around the coolant temp sensor and causes the sensor to read a cooler tempatures. 2) There have been cases that the termostate is stock in the open position. 3) The coolant temp sensor is bad. In most cases a good coolant flush corrects the problem.

**chico** · 02-11-07 07:37 PM

i get P0128 about twice a week usually on the same days when i return home very late at night and its really cold, also im only getting it on highways when i go over 120km/h.
Same here i`ll wait till warmer weather and see how it acts, but if its only a winter thing i can live with it

**DMC-12** · 02-11-07 09:05 PM

I just hit 81k... so I assume a good flush and fill is in order, no matter what.

Funny... I drove up to Milwaukee and back today... and its been about 30F degrees all day.. and it has not thrown the code for the past two (slightly) warmer days. Weirdness.

**54inches** · 10-27-07 04:35 PM

I have 34,000 miles on mine and it just did it right after we ahd a cold snap. I cleared the code and I am going to see how it is doing.

**Top-Gun** · 10-27-07 04:48 PM

My 04 with 70,000 miles has had this same code pop up a couple times, I just clear it and it doesn't come back for a month or so. I also assumed it was just a T-stat bypassing a bit but what Nels said makes alot of sense. Might be worth pulling that sensor and seeing if theres any build-up on it.

**chico** · 10-28-07 08:00 PM

actually, now that the temp. is low i got the bloody code the other day

**wait4me6920** · 10-28-07 08:16 PM

Originally Posted by 54inches

I have 34,000 miles on mine and it just did it right after we ahd a cold snap. I cleared the code and I am going to see how it is doing.

Whoa, a cold snap in Baytown... Dropped below 80 degrees, did it?

**54inches** · 10-28-07 10:03 PM

I think it feels great, but there are people shivering around here. Of course I think 110 feels great too!

**asoares** · 11-07-07 09:24 AM

Originally Posted by B0000rt

I'm in the same situation, I don't think much can go wrong if you leave it how it is for another few months, the stat open and all.

I personally already have the stat w/ me, and I'm just waiting for the warmer weather. I believe you need a few more gaskets as you're going to have to take off the Intake Manifold to get at it. Lemme scan you the instructions.

Here you go:

Thanks for the info. I was a little catious about downloading a pdf but it seems lagite and has alot of good info. thanks!

**Coma** · 11-07-07 10:15 AM

Whenever it gets really cold, like under 30ºF, my car outputs a "Check Coolant Level" message. I know my coolant level is fine, and this goes away shortly anyways. I just think it's weird that it does this. I just ignore it.

My car is a 2006 with only 30K miles on it.

**54inches** · 11-15-07 11:11 PM

I cleared my code about a month ago and nothing yet. I have waited to turn on the heater on until it is up to operating temperature. No codes.

**54inches** · 11-16-07 11:17 PM

Well, I had to open my big mouth.

I got in the car today and it threw the code AGAIN.

I am thinking about doing a flush, but she only has 35,000 miles on her.

Where did you guys buy your tstat and your gaskets? Vatozone had nothing!