SaturnFans.com
what's new (beta) - classifieds - forums - photos


Go Back   SaturnFans.com Forums > Models > Saturn Ion > Ion Tech
Register FAQ Members List Groups Calendar Chat Room Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
Old 01-08-2018, 08:50 PM   #1
freemancomputer
Junior Member
freemancomputer has a spectacular aura aboutfreemancomputer has a spectacular aura about
 
Join Date: Aug 2010
Posts: 33
Default intermittent p0128

Hello all. I have a 2007 Ion. The temp gauge will randomly drop with no reading. When the gauge is reading 0 after a little bit the computer throws a p0128.

When the gauge is a 0 and the check engine light is on I can clear the code and the gauge will rise right away. When the gauge is not working the heat blows warm but not hot air. As soon as I clear the code the heat starts working as it should.

We have a few warm days coming up and I would like to take advantage of that to get this working. I have read 1 of 3 things can cause this, the thermostat, coolant temperature Sensor and the float sensor in the coolant tank. Because I can clear the code and the gauge works I don't think that its the thermostat and because its not giving me low coolant I don't see it being the flat sensor. I wanted to get your ideas before I started throwing parts at the car.

Thank you in advance for your help.

REWARD EXCELLENCE!

Add to freemancomputer's Reputation
Rate the quality of this post and help freemancomputer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
freemancomputer is offline   Reply With Quote
SaturnFans.com Sponsored Links
Old 01-08-2018, 10:12 PM   #2
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 41,452
 

2003 L-Series 3.0L Sedan
Default Re: intermittent p0128

The coolant float sensor is a go/no go sensor to indicate whether or not coolant level is correct. It will not generate an error code.

P0128 is most likely a worn thermostat because no one can tell a bad one from a good one by eye (with one exception). Since the coolant sensor is used in the EFI system, its serves two purposes - continuously sends temperature signals to the engine computer so correct air/fuel mixtures are made (among other sensors) and show an analog or digital display of coolant temperatures. Since the sensor is electronic, the signals are used by the engine computer to drive the temperature needle. If you are not sure whether the sensor or t-stat is faulty, you can use a reader to display sensor signals. SInce the engine computer already interprets the signals, a reader plugged into the OBD II port should display actual temperatures. To determine whether or not the sensor is faulty is easy.

If you have a reader that displays coolant temps, the reader can also display intake air temps since both are thermistors. Best comparison of air and coolant temps is before the first engine start of the day when the engine is at ambient temps. The intake air and coolant sensors should be displaying temps within five degrees of each other (reference-1). Engine running should show the coolant sensor temps rising until reaching thermostat regulating temps, 195F (reference-2). The rising coolant temps indicates the sensor is operating as designed. If not operating correctly, the display either freezes when you know the engine is warming up physically or temps will be erratic. How do you tell the difference between a worn t-stat and faulty sensor? Knowledge and careful observation. And some background facts to eliminate guessing.

Every P0128 error code is about faulty t-stats. My L300 and a Nissan Sentra generated this code. Both t-stats ran cooler as shown on a reader. Both t-stats were replaced and the error code went away. Other Saturn models also had this error code. T-stat replacement is the cure.

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 01-08-2018, 10:54 PM   #3
freemancomputer
Junior Member
freemancomputer has a spectacular aura aboutfreemancomputer has a spectacular aura about
 
Join Date: Aug 2010
Posts: 33
Default Re: intermittent p0128

Quote:
Originally Posted by fdryer View Post
The coolant float sensor is a go/no go sensor to indicate whether or not coolant level is correct. It will not generate an error code.

P0128 is most likely a worn thermostat because no one can tell a bad one from a good one by eye (with one exception). Since the coolant sensor is used in the EFI system, its serves two purposes - continuously sends temperature signals to the engine computer so correct air/fuel mixtures are made (among other sensors) and show an analog or digital display of coolant temperatures. Since the sensor is electronic, the signals are used by the engine computer to drive the temperature needle. If you are not sure whether the sensor or t-stat is faulty, you can use a reader to display sensor signals. SInce the engine computer already interprets the signals, a reader plugged into the OBD II port should display actual temperatures. To determine whether or not the sensor is faulty is easy.

If you have a reader that displays coolant temps, the reader can also display intake air temps since both are thermistors. Best comparison of air and coolant temps is before the first engine start of the day when the engine is at ambient temps. The intake air and coolant sensors should be displaying temps within five degrees of each other (reference-1). Engine running should show the coolant sensor temps rising until reaching thermostat regulating temps, 195F (reference-2). The rising coolant temps indicates the sensor is operating as designed. If not operating correctly, the display either freezes when you know the engine is warming up physically or temps will be erratic. How do you tell the difference between a worn t-stat and faulty sensor? Knowledge and careful observation. And some background facts to eliminate guessing.

Every P0128 error code is about faulty t-stats. My L300 and a Nissan Sentra generated this code. Both t-stats ran cooler as shown on a reader. Both t-stats were replaced and the error code went away. Other Saturn models also had this error code. T-stat replacement is the cure.
The Thermostat is under warranty so changing that is no big deal. I figured that the float wouldn't be the cause of the code. My question is why would the gauge read nothing and throw the code than as soon as I clear the code it will read the temp? Some times when the code is up the gauge will just start working again. I understand how the cooling system works I'm just wondering why a thermostat that is stuck open would cause the gauge to read nothing.

REWARD EXCELLENCE!

Add to freemancomputer's Reputation
Rate the quality of this post and help freemancomputer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
freemancomputer is offline   Reply With Quote
Old 01-09-2018, 01:03 AM   #4
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 41,452
 

2003 L-Series 3.0L Sedan
Default Re: intermittent p0128

As suggested, plug in a reader capable of displaying coolant temps. Either you see the same intermittent change in temperature or not. Examine the coolant sensor connection too. Guessing is easy, troubleshooting with known methods may be more involved but not difficult. Your choice.

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 01-09-2018, 03:20 PM   #5
freemancomputer
Junior Member
freemancomputer has a spectacular aura aboutfreemancomputer has a spectacular aura about
 
Join Date: Aug 2010
Posts: 33
Default Re: intermittent p0128

Quote:
Originally Posted by fdryer View Post
As suggested, plug in a reader capable of displaying coolant temps. Either you see the same intermittent change in temperature or not. Examine the coolant sensor connection too. Guessing is easy, troubleshooting with known methods may be more involved but not difficult. Your choice.
I understand the troubleshooting part that's not that bad. I will be going to to check the temp readings today or tomorrow. What I'm trying to understand is why a fatally Thermostat would cause this. The stat is mechanical so why would clearing the code fix it even for a little bit?

REWARD EXCELLENCE!

Add to freemancomputer's Reputation
Rate the quality of this post and help freemancomputer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
freemancomputer is offline   Reply With Quote
Old 01-10-2018, 03:00 AM   #6
ruley73
Master Member
ruley73 is a splendid one to beholdruley73 is a splendid one to beholdruley73 is a splendid one to beholdruley73 is a splendid one to beholdruley73 is a splendid one to beholdruley73 is a splendid one to behold
 
ruley73's Avatar
 
Join Date: Aug 2006
Location: Is this heaven?....No, it's Iowa!
Posts: 2,913
 

2007 ION-2 Quad Coupe
Default Re: intermittent p0128

Quote:
Originally Posted by freemancomputer View Post
I understand the troubleshooting part that's not that bad. I will be going to to check the temp readings today or tomorrow. What I'm trying to understand is why a fatally Thermostat would cause this. The stat is mechanical so why would clearing the code fix it even for a little bit?
A bad thermostat that stays open causes the engine operating temperature to stay lower than it should or at the very least take significantly longer for the engine to warm up. A bad engine coolant temp sensor is interpreted the same way by the ECM. That is how either a bad ECTS or a bad thermostat that is stuck open can trgger code P0128.

Also, FYI troublecodes don't affect how the heat works in your Ion. It is impossible for clearing the codes to make the heater work better as you previously stated. The HVAC vent mode and temperature controls are manually adjusted with cables attached to the knobs. The only thing that is electronically controlled (aside from A/C compressor and blower motor) is the recirculation door.

...
2007 Ion 2 Quad Coupe 5-speed manual 179K miles
2007 Chevy Equinox LT 190K miles

Last edited by ruley73; 01-10-2018 at 03:06 AM..

REWARD EXCELLENCE!

Add to ruley73's Reputation
Rate the quality of this post and help ruley73 reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
ruley73 is offline   Reply With Quote
Old 01-10-2018, 04:11 AM   #7
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 41,452
 

2003 L-Series 3.0L Sedan
Default Re: intermittent p0128

A worn out t-stat can't be fixed by resetting error codes (that come back). Resetting this error code (P0128) that comes back means you haven't understood the relationship between t-stat and coolant sensor. The t-stat affects the coolant sensor, not the other way around since a t-stat physically regulates engine coolant operating temps (not the coolant sensor). As a sensor, all it does is 'sense' surrounding temps (coolant) and sends signals to the engine computer. The coolant sensor is just a sensor and doesn't regulate coolant operating temperatures.

If I were you, I would simply replace the t-stat, changing antifreeze while your at it or reuse it if its clean and filtered before reuse.

If you really need to understand some basics; remove the coolant sensor (with enough wire length), turn on ignition (engine off), dip the coolant sensor in a container of boiling water (as close to it anyway) and observe your reader and temperature display. Without any delay and using a HOT container of plain water, the coolant sensor immersed in hot water is immediately sensed and signals are interpreted for reader and gauge displays.You can do the same with a t-stat but you'll need a precise method to monitor water temperatures to observe when it begins to open. One is electronic, the other is mechanical. Understanding how they work together is part of EFI systems not understood by many. A fully automated EFI system with auto diagnostic programs with error codes can make some repairs easy or difficult. The difficulty lies in unfamiliarity with how engines run with EFI systems, error codes produced by diagnostic programs and interpreting where a problem lies. Is it in the electronics, mechanical, wires, power, computer?

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 01-10-2018, 08:23 PM   #8
freemancomputer
Junior Member
freemancomputer has a spectacular aura aboutfreemancomputer has a spectacular aura about
 
Join Date: Aug 2010
Posts: 33
Default Re: intermittent p0128

Quote:
Originally Posted by fdryer View Post
A worn out t-stat can't be fixed by resetting error codes (that come back). Resetting this error code (P0128) that comes back means you haven't understood the relationship between t-stat and coolant sensor. The t-stat affects the coolant sensor, not the other way around since a t-stat physically regulates engine coolant operating temps (not the coolant sensor). As a sensor, all it does is 'sense' surrounding temps (coolant) and sends signals to the engine computer. The coolant sensor is just a sensor and doesn't regulate coolant operating temperatures.

If I were you, I would simply replace the t-stat, changing antifreeze while your at it or reuse it if its clean and filtered before reuse.

If you really need to understand some basics; remove the coolant sensor (with enough wire length), turn on ignition (engine off), dip the coolant sensor in a container of boiling water (as close to it anyway) and observe your reader and temperature display. Without any delay and using a HOT container of plain water, the coolant sensor immersed in hot water is immediately sensed and signals are interpreted for reader and gauge displays.You can do the same with a t-stat but you'll need a precise method to monitor water temperatures to observe when it begins to open. One is electronic, the other is mechanical. Understanding how they work together is part of EFI systems not understood by many. A fully automated EFI system with auto diagnostic programs with error codes can make some repairs easy or difficult. The difficulty lies in unfamiliarity with how engines run with EFI systems, error codes produced by diagnostic programs and interpreting where a problem lies. Is it in the electronics, mechanical, wires, power, computer?
I think there is a misunderstanding on my question. Let me try again. The temp gauge drops to give no reading, after a little while the code comes up. As soon as the code is cleared the gauge reads as it should. I was out today and the gauge dropped. I checked the codes right way and the p0128 was pending. I cleared the pending code and the gauge when back to reading a running temp. This happened with in 10 seconds of the gauge dropping. Before the gauge dropped to 0 the temp was running at 185-190, when the gauge dropped the reading when to 0 and right back up when the code cleared.

So the question that I have is why a thermostat being stuck open would cause the gauge and the sensor to read 0 then rise back to running temp as soon as the code is cleared? I would ask if the gauge is connected to the code but sometimes while the code is up the gauge will work as normal. If the thermostat was stuck open shouldn't the gauge still work just with a low running temp?

REWARD EXCELLENCE!

Add to freemancomputer's Reputation
Rate the quality of this post and help freemancomputer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
freemancomputer is offline   Reply With Quote
Old 01-10-2018, 10:14 PM   #9
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 41,452
 

2003 L-Series 3.0L Sedan
Default Re: intermittent p0128

Ok, let's go with your theory. If you believe the coolant sensor is faulty did you examine the connections to it yet? Electronics requires good connections and if you believe this is an electronics problem you're left to consider the sensor, wiring and engine computer as possible problems. Check for good electrical connections before suspecting a faulty sensor. No one can tell you which way to proceed as its your decision to go either with a t-stat or coolant sensor or both.

A coolant sensor takes about a minute to remove and replace. If its in an inaccessible place, more time. Replacing a thermostat requires draining coolant before removing a hose or more to remove the t-stat housing to replace it. If antifreeze isn't reused then fresh coolant is needed. A drain and flush is recommended when a t-stat is replaced. You always have choices.

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 01-11-2018, 03:12 PM   #10
freemancomputer
Junior Member
freemancomputer has a spectacular aura aboutfreemancomputer has a spectacular aura about
 
Join Date: Aug 2010
Posts: 33
Default Re: intermittent p0128

Quote:
Originally Posted by fdryer View Post
Ok, let's go with your theory. If you believe the coolant sensor is faulty did you examine the connections to it yet? Electronics requires good connections and if you believe this is an electronics problem you're left to consider the sensor, wiring and engine computer as possible problems. Check for good electrical connections before suspecting a faulty sensor. No one can tell you which way to proceed as its your decision to go either with a t-stat or coolant sensor or both.

A coolant sensor takes about a minute to remove and replace. If its in an inaccessible place, more time. Replacing a thermostat requires draining coolant before removing a hose or more to remove the t-stat housing to replace it. If antifreeze isn't reused then fresh coolant is needed. A drain and flush is recommended when a t-stat is replaced. You always have choices.
So I replaced both the thermostat and the sensor, the wires look good. Once I had the car back up and running I tested the old thermostat. It opened at 181 and closed at about 175 just as it is designed to do.

REWARD EXCELLENCE!

Add to freemancomputer's Reputation
Rate the quality of this post and help freemancomputer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
freemancomputer is offline   Reply With Quote
Old 01-11-2018, 04:22 PM   #11
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 41,452
 

2003 L-Series 3.0L Sedan
Default Re: intermittent p0128

When you posted warm heater output, what was the coolant temperature, reader display, before replacing parts? What's coolant temps now after warning up?

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 01-26-2018, 02:03 PM   #12
freemancomputer
Junior Member
freemancomputer has a spectacular aura aboutfreemancomputer has a spectacular aura about
 
Join Date: Aug 2010
Posts: 33
Default Re: intermittent p0128

Quote:
Originally Posted by fdryer View Post
When you posted warm heater output, what was the coolant temperature, reader display, before replacing parts? What's coolant temps now after warning up?
Ok its been awhile, been putting a clutch in my other car. Before and after the parts were replaced reads about 195 when warmed up. It jumps a little if the car is idling for a few minutes. Note that it read 0 when the gauge was not working. Since I put in the sensor the gauge has been acting as it should with no drops in the reading and no codes.

Now if I can get the wife to drive it with out rear ending a truck that would be nice. New hood, latch and headlight. No real damage.

REWARD EXCELLENCE!

Add to freemancomputer's Reputation
Rate the quality of this post and help freemancomputer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
freemancomputer is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
P0128 code on 03 Vue cooxl231 Vue General 32 04-18-2012 10:21 AM
P0128 - 2002 Sl2 - Help TXSaturn02 S-Series Tech 9 10-28-2010 10:45 PM
Code p0128 nevets S-Series Tech 2 01-03-2009 11:48 PM
P0128 code issue bubba1ton S-Series General 7 05-17-2006 04:25 AM
Thermostat - P0128 LW300 '02 BlueVette99 L-Series General 1 01-31-2006 02:06 PM


All times are GMT -4. The time now is 12:16 AM.

Advanced Forum Search | Advanced Photo Search


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
SaturnFans.com. The Saturn Enthusiasts Site.