Check Engine Light....P0128 Code?
06-03-2009, 02:55 PM
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Check Engine Light....P0128 Code?
Ok So when the light came on I took the car up to Advance Auto Parts so they can check and see why the light came on. The code was P0128 meaning something like the radiatore/ coolant was below normal temp. (idk if im right). Is this true? How do i fix this?
06-03-2009, 07:18 PM
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P0128 Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature ECM
Generally means you need a new thermostat. Cheap part, pain in the ass to actually get to.
Generally means you need a new thermostat. Cheap part, pain in the ass to actually get to.
06-04-2009, 08:17 AM
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do your low speed fans run constantly? cus im having the same code now and my fans wont shut off.. they turn on as soon as i flip the key on
06-04-2009, 11:36 AM
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Idk About the low speed fans. I feel like a noob sayining that. But I started paying attention to my temps while driving and when it turns on its at 185/184 but then it drops to 175 then further down the road it stays constant at 165/163
06-04-2009, 12:14 PM
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Yeah 165 is pretty low. I usually stay above 176~180 cruising. If it drops that low while you are driving then I would concur with the others here, thermostat. And as with everyone else, I have no freaking clue how to replace it...
06-05-2009, 03:26 AM
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Ok Update: It seems the temp is staying at 145. So I found a place that I can get it for $25 from a gm part dealer online. I will check out my Haynes book to see what I can do. If I can fix it and i'm successful, I will try and post a "How to" about it.
06-11-2009, 12:30 AM
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Update: ok so I filled up the tvs coolant resevoir. 2 days later its empty?! Plus the temp is now saying its 219. I ordered the thermostat. But what would cause the coolant to drain so quick? Help!!
06-11-2009, 12:38 AM
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I don't have a coolant draining problem but my car too has the problem of running at like 160 degrees and then when you come to a stop the car starts to heat up pretty quickly.
06-11-2009, 04:13 AM
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whenever you sit and idle, the radiator doesn't get air flowing past it like when you're cruising, so it is less efficient at removing heat, so yea the temp goes up. how high up it goes is up to the efficiency of your cooling system. i've hit 215 idling in the summer for 5 minutes at a light. no biggy, aluminum needs much higher than that to warp 
if you're staying at 145, check the fans too. when the coolant temperature sensor is fucked, it sends screwy signals to the pcm, and commands the fans to be turned on. your temperature guage is not based on coolant temp, hence why you can pull the plug on the ect and still have a temperature reading. 145 sounds like the fans are on AND the thermostat is flowing too soon. even if the therm is open too soon, or perhaps stuck open, check something: how quickly is your car getting to 145? slow, like 10-15 minutes of driving = stuck open, fast, like normal driving of 5 minutes or so = working, but out of its specifications, aka opening too soon.
if you're fans are on when they shouldn't be, it's usually the temp sensor. if it is operating within its range, aka working but is slightly off, it'll command the fans on too soon (cool). fans for the cobalt SC turn on at 225 degrees (tested @ my school's auto lab)
get your car up to 145-160 where u say it stays. pull over, and see if the fans are on. if they are, check the voltage @ the etc. you can carefully backpobe it, and tell me the voltages you get since i tested mine. replace if necessary. the fans shouldn't come on too soon now, and your temps will return to normal. if they don't, change the thermostat too. then you'll have peace of mind of a properly flowing thermostat and a properly working coolant temp sensor.
as for the 'tvs reservior' what are you referring to? did you drain the fluid?? when the thermostat opens and routes some more fluid throughout the system, you'll need to top it off after it cools. 2 quarts going to nowhere's land is fine... unless you keep adding and adding, then you have a leak or a blown head gasket, which i doubt.
if you're staying at 145, check the fans too. when the coolant temperature sensor is fucked, it sends screwy signals to the pcm, and commands the fans to be turned on. your temperature guage is not based on coolant temp, hence why you can pull the plug on the ect and still have a temperature reading. 145 sounds like the fans are on AND the thermostat is flowing too soon. even if the therm is open too soon, or perhaps stuck open, check something: how quickly is your car getting to 145? slow, like 10-15 minutes of driving = stuck open, fast, like normal driving of 5 minutes or so = working, but out of its specifications, aka opening too soon.
if you're fans are on when they shouldn't be, it's usually the temp sensor. if it is operating within its range, aka working but is slightly off, it'll command the fans on too soon (cool). fans for the cobalt SC turn on at 225 degrees (tested @ my school's auto lab)
get your car up to 145-160 where u say it stays. pull over, and see if the fans are on. if they are, check the voltage @ the etc. you can carefully backpobe it, and tell me the voltages you get since i tested mine. replace if necessary. the fans shouldn't come on too soon now, and your temps will return to normal. if they don't, change the thermostat too. then you'll have peace of mind of a properly flowing thermostat and a properly working coolant temp sensor.
as for the 'tvs reservior' what are you referring to? did you drain the fluid?? when the thermostat opens and routes some more fluid throughout the system, you'll need to top it off after it cools. 2 quarts going to nowhere's land is fine... unless you keep adding and adding, then you have a leak or a blown head gasket, which i doubt.
06-11-2009, 04:40 AM
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thermostat is gone, figuratively. threw the same code on my lsj a few times a while back. took it in to the dealer under warranty thank god. $70 part. 5-7hrs labor. if you open the hood and look at the engine, its placed at the bottom of the engine, on the right side, near the fire wall
06-11-2009, 11:40 AM
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well that must be the same problem im having.. my fans constantly run and ive replaced my engine coolant temp sensor which hasnt seemed to fix the problem.. i guess ill change my thermo but i dont see how that would stop my fans from running..
06-11-2009, 02:19 PM
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^^^ sometimes it can be a bad wire to the ECT sensor. the signal the PCM gets to turn the fans on is from the ECT sensor. when ya pull the plug on it, you throw a code, and it commands the fans on at all times. this is so that if there's ever a miscommunication with the sensor, it defaults to fans on to keep the car cool.
another point in the system that can go fubar is the fan relays, make sure they aren't shorted or something. if they are, then forget the signal from a working or non working ECT... power just gets constantly routed to the fans regardless.
as for the thermo... alldata says its about an hour for labor. i haven't looked for it yet myself, but it's located down and back a ways yes. says to remove the surge reservior hose from the top of the therm, then remove the oil cooler lines from it as well, then pop the top of the thermostat housing, replace, reinstall. how the hell could changing a thermostat be a 5-7 hour job?? GM sure is loco.
since i can't copy and pasta from alldata or mitchell 1 ondemand5, such a pain... i took a screenshot and got this from mitchellsondemand.com:
if it's too small, hold ctrl and hit + to blow up the web page. ctrl and 0 to go back to normal. it details how to remove and reinstall, deff not a 5-7 hour job! gonna look at it in a few under my hood.
another point in the system that can go fubar is the fan relays, make sure they aren't shorted or something. if they are, then forget the signal from a working or non working ECT... power just gets constantly routed to the fans regardless.
as for the thermo... alldata says its about an hour for labor. i haven't looked for it yet myself, but it's located down and back a ways yes. says to remove the surge reservior hose from the top of the therm, then remove the oil cooler lines from it as well, then pop the top of the thermostat housing, replace, reinstall. how the hell could changing a thermostat be a 5-7 hour job?? GM sure is loco.
since i can't copy and pasta from alldata or mitchell 1 ondemand5, such a pain... i took a screenshot and got this from mitchellsondemand.com:
if it's too small, hold ctrl and hit + to blow up the web page. ctrl and 0 to go back to normal. it details how to remove and reinstall, deff not a 5-7 hour job! gonna look at it in a few under my hood.
Last edited by SprChrg4Life; 06-11-2009 at 02:19 PM. Reason: Automerged Doublepost
06-11-2009, 02:50 PM
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why? so that when you run too cool you won't throw a code? running too cool won't allow for closed loop fuel monitoring, which if any1 gives a damn about $$ and fuel efficiency is kinda important so that we don't use excess fuel. but i guess a good tune lets your car use the proper amount of fuel, might as well disable the 02 sensors while they're at it.
if you modded your car, it should be running a bit hot anyways, due to more power, unless ya did a fan mod to run em when desired, and got a lower temp thermostat, bigger radiator, etc. etc. 180* is the place to be, maybe 170*. whatever is required for closed loop, i believe 160*.
if you modded your car, it should be running a bit hot anyways, due to more power, unless ya did a fan mod to run em when desired, and got a lower temp thermostat, bigger radiator, etc. etc. 180* is the place to be, maybe 170*. whatever is required for closed loop, i believe 160*.
06-11-2009, 08:43 PM
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why? so that when you run too cool you won't throw a code? running too cool won't allow for closed loop fuel monitoring, which if any1 gives a damn about $$ and fuel efficiency is kinda important so that we don't use excess fuel. but i guess a good tune lets your car use the proper amount of fuel, might as well disable the 02 sensors while they're at it.
if you modded your car, it should be running a bit hot anyways, due to more power, unless ya did a fan mod to run em when desired, and got a lower temp thermostat, bigger radiator, etc. etc. 180* is the place to be, maybe 170*. whatever is required for closed loop, i believe 160*.
if you modded your car, it should be running a bit hot anyways, due to more power, unless ya did a fan mod to run em when desired, and got a lower temp thermostat, bigger radiator, etc. etc. 180* is the place to be, maybe 170*. whatever is required for closed loop, i believe 160*.
06-12-2009, 08:00 AM
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^^^ sometimes it can be a bad wire to the ECT sensor. the signal the PCM gets to turn the fans on is from the ECT sensor. when ya pull the plug on it, you throw a code, and it commands the fans on at all times. this is so that if there's ever a miscommunication with the sensor, it defaults to fans on to keep the car cool.
another point in the system that can go fubar is the fan relays, make sure they aren't shorted or something. if they are, then forget the signal from a working or non working ECT... power just gets constantly routed to the fans regardless.
as for the thermo... alldata says its about an hour for labor. i haven't looked for it yet myself, but it's located down and back a ways yes. says to remove the surge reservior hose from the top of the therm, then remove the oil cooler lines from it as well, then pop the top of the thermostat housing, replace, reinstall. how the hell could changing a thermostat be a 5-7 hour job?? GM sure is loco.
since i can't copy and pasta from alldata or mitchell 1 ondemand5, such a pain... i took a screenshot and got this from mitchellsondemand.com:
if it's too small, hold ctrl and hit + to blow up the web page. ctrl and 0 to go back to normal. it details how to remove and reinstall, deff not a 5-7 hour job! gonna look at it in a few under my hood.
another point in the system that can go fubar is the fan relays, make sure they aren't shorted or something. if they are, then forget the signal from a working or non working ECT... power just gets constantly routed to the fans regardless.
as for the thermo... alldata says its about an hour for labor. i haven't looked for it yet myself, but it's located down and back a ways yes. says to remove the surge reservior hose from the top of the therm, then remove the oil cooler lines from it as well, then pop the top of the thermostat housing, replace, reinstall. how the hell could changing a thermostat be a 5-7 hour job?? GM sure is loco.
since i can't copy and pasta from alldata or mitchell 1 ondemand5, such a pain... i took a screenshot and got this from mitchellsondemand.com:
if it's too small, hold ctrl and hit + to blow up the web page. ctrl and 0 to go back to normal. it details how to remove and reinstall, deff not a 5-7 hour job! gonna look at it in a few under my hood.
06-12-2009, 10:47 PM
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damn u tried the relay? did you test the relay with a 9volt? google how to test a relay it's easy. and the thermo is easy, just remove the hoses going to it with pliers on the clamps, then use a swivel socket to get down in there. done.
06-13-2009, 12:56 PM
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lol man i searched that and im completely inefficient when it comes to electrical stuff! i read that n it was like i was tryin to learn hebrew! what i did was switch out the relays and when i pulled the low speed fan one out they stopped. obviously. but then i replaced it with another one and it came right back on..
06-13-2009, 03:59 PM
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who fix your car? where? how much? I need to fix my car soon.please send me a pm with that info.
