Any GM techs out there? p0128 and "---" Temp readout
12-24-2009, 03:31 PM
#26
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This is starting to point all towards the ECM. I replaced the temp sensor today and nothing. The engine doesnt run hot and it never jumped up and down on the temperatures. I just have A/C problems and dashes. What would be the course of action to take now? Replace the ECM? I stock reflashed it with a GM tech 2 at a dealership back in May or June and just after that the A/C stopped working. But before this I had the --- problem. I also had a dyno tune from a local company who did an awful job a couple years ago but now its on stock tune from the reflash back in May.
12-24-2009, 05:09 PM
#28
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checked the temp sensor wiring. i want to believe its the thermostat because i cant find a 2.4 ECM thatll work on my car. would it make sense to take it to the dealer and get it reflashed or updated? where else can i check? this problem is kicking my ass and im trying to sell my car but wont put it out until the CEL and A/C are fixed and this problem seems to solve both.
Thanks Maven
Thanks Maven
12-24-2009, 06:00 PM
#29
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When the P0128 is set, the a/c will not work and the temp. gauge on the cluster will read ---. Had the same problem with an 06 HHR w/ the 2.2 at work a couple months back. The seal on the thermostat was actually pinched and letting coolant flow through it while it was closed. Anyway, a thermostat will most likley fix your problem.
Now, I bet if you have the code cleared...your a/c will work and the temp gauge on your cluster will work
Now, I bet if you have the code cleared...your a/c will work and the temp gauge on your cluster will work
12-24-2009, 06:02 PM
#30
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When the P0128 is set, the a/c will not work and the temp. gauge on the cluster will read ---. Had the same problem with an 06 HHR w/ the 2.2 at work a couple months back. The seal on the thermostat was actually pinched and letting coolant flow through it while it was closed. Anyway, a thermostat will most likley fix your problem.
Now, I bet if you have the code cleared...your a/c will work and the temp gauge on your cluster will work
Now, I bet if you have the code cleared...your a/c will work and the temp gauge on your cluster will work
is there some kind of detailed write up or how-to for this replacement, I havent seen one yet from the other 10-15 coolant threads ive seen
12-24-2009, 06:04 PM
#31
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I know that....
I was just saying if you clear the code and the cluster works...you know the --- readout is related to the p0128 code. Anyway, put a thermostat in it, clear the code and be on your way.
I was just saying if you clear the code and the cluster works...you know the --- readout is related to the p0128 code. Anyway, put a thermostat in it, clear the code and be on your way.
12-24-2009, 06:06 PM
#32
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You say that if I clear the code and everything works then the problem is for sure the thermostat?
12-24-2009, 06:08 PM
#33
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I know if you clear that code the a/c and DIC will work....I had the same thing happen to me on an HHR I was working on
And yes, when the p0128 is set it is almost always a thermostat issue....
And yes, when the p0128 is set it is almost always a thermostat issue....
12-24-2009, 07:19 PM
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12-25-2009, 12:51 AM
#35
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I have a 2007 Chevy Cobalt LS that has been throwing a p0128 code recently coupled with the fact that when it does the engine temp readout on the DIC reads "---" instead of a temp. I was told that the most likely culprit was the engine temp sensor (coolant sensor) which I had replaced a month ago and it did not help. Car has 47000 miles so warranty is not an option. The problem comes and goes but in the last month the problem has been more and more frequent. Also now the car has a loud noise when accelerating past 3000 rpms, sounded to me at first like a leak in the exhaust somewhere in the engine compartment but now I'm not too sure. Also on startup sounds like I have a loose belt or something. I have been told by a parts guy at a local dealership to replace the thermostat and flush the coolant and refill but when I posted a thread about this before the general concensus seemed to be that the thermostat would have nothing to do with the temp readout in the DIC.
What should I do next? Could I have caused damage to the engine? Any help would be greatly appreciated. I think I either have a few problems going on at once or I am really afraid that this original problem has now caused some engine damage that would cause the new noise. Thanks!
What should I do next? Could I have caused damage to the engine? Any help would be greatly appreciated. I think I either have a few problems going on at once or I am really afraid that this original problem has now caused some engine damage that would cause the new noise. Thanks!
1: The temp sensor is not sending the data (Change sensor)
2: The computer is not processing the data (Change Computer)
3: The computer is not recieving data that is being sent (Wireing between the two)
12-25-2009, 01:01 AM
#36
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I say check plugs and wireing for the temp problem... if the thermo was messed up, youd just get messed up temp readings, not ---, a reading of --- seems to indiate that the computer is not getting any data from the temp sensor.
1: The temp sensor is not sending the data (Change sensor)
2: The computer is not processing the data (Change Computer)
3: The computer is not recieving data that is being sent (Wireing between the two)
1: The temp sensor is not sending the data (Change sensor)
2: The computer is not processing the data (Change Computer)
3: The computer is not recieving data that is being sent (Wireing between the two)
12-25-2009, 02:31 PM
#38
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it is. my thermostat is fine. the temp readout is always normal and the temp sensor was replaced and nothing happened. it only comes on when either tampered with or 65+ degrees or when it feels like it. My ECM has also been through a lot. Been through a bunch of tunes and flashes and crap and stock flashes and bad flashes.
12-25-2009, 03:35 PM
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No, if it was open then my car would be running relatively cool all the time because it would be getting constant coolant through it. If it was closed then my engine would be frickin hot or blown up by now because its been like this for a while and I push my car more than I should. This of course is an experience diagnosis by my father who has been working on cars for about 47 years now.
12-25-2009, 03:44 PM
#41
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The thermostat doesn't have to be stuck completley open for this code to set. That ecm is monitoring the temperature in the engine in a certain time frame and looking for it to reach a certain temerature in that amount of time. And when it doesn't reach that temp. the p0128 will set...I'm just tryin to help here man. But if you'd rather spend cash on an ecm or something instead of a 20 dollar thermostat, that's all good. Just saying what I see from working on these things....I am a master certified tech too btw lol
Just saying what I see from working on these things....I am a master certified tech too btw lol
12-25-2009, 04:02 PM
#42
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I mean. Check out the symptoms. Which of the 2 is more likely affected by cold weather because thats the majority of the problem. Any time the weather reaches and stays below about 60, this code is thrown and stays on for the whole winter pretty much. If its 70+ it usually goes away. It never comes on in the Summer. In your knowledge, what kind of bullshit is that?
12-25-2009, 04:18 PM
#44
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12-25-2009, 04:22 PM
#45
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Yup....I replaced one an a 2.4 HHR a few months ago actually.....p0128 was set, temp. indicator showed ---, and a/c inop....the indicator and a/c being disabled is what the pcm/bcm does when there in a cooling system dtc set. Anyway, pulled the thermostat out and the inner seal of the thermostat was pinched and letting coolant flow by. New thermostat was put in and no troubles out of the car since.
12-25-2009, 04:57 PM
#46
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Yup....I replaced one an a 2.4 HHR a few months ago actually.....p0128 was set, temp. indicator showed ---, and a/c inop....the indicator and a/c being disabled is what the pcm/bcm does when there in a cooling system dtc set. Anyway, pulled the thermostat out and the inner seal of the thermostat was pinched and letting coolant flow by. New thermostat was put in and no troubles out of the car since.
12-26-2009, 12:53 PM
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12-27-2009, 09:59 PM
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Found some interesting data. The numbers seem to show up when the coolant reaches about 135 degrees or something. The other day it showed up at 138 from --- and it went up to a max of 151 and stayed around 145. Then the next day I turned on my car and it was showing numbers again and then I started driving, after about 5 mins or less it was only at like 120 and then it just went to --- again. It seems to want to be at like 135+ or it just goes to ---. Also isnt 145 running kinda cold? This was all primarily done in 40 degree weather.