Taking too long to get to operating temperature, code P0128

Tiny
ALEXTTT
  • MEMBER
  • 2005 PONTIAC G6
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 106,000 MILES
For the last couple of days my car has not been getting to the normal operation temperature it been getting to 160 degrees and usually it’s at 200. I got a check engine code for P0128 saying the car is taking too long to heat up. I’m planning to replace the thermostat tomorrow. Today I went to check the upper hose where the thermostat is and it was extremely hot to touch.
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Monday, November 9th, 2020 AT 6:27 PM

13 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The hose being hot is normal if the engine was just turned off or running. As far as the code, the thermostat is the likely cause. If the engine doesn't warm up fast enough because the thermostat isn't allowing it to, it increases the emissions put out by the vehicle which can result in the code you mentioned. So what you have suggested makes sense to repair the issue.

__________

Here is a link you may find helpful. It explains in general how a thermostat is replaced.

https://www.2carpros.com/articles/replace-thermostat

__________

Here are the directions specific to your vehicle. The attached pics correlate with the directions.

__________

2005 Pontiac G6 V6-3.5L VIN 8
Procedures
Vehicle Engine, Cooling and Exhaust Cooling System Thermostat Service and Repair Procedures
PROCEDURES
Thermostat Replacement

Tools Required
J38185 Hose Clamp Pliers

Removal Procedure

pic 1

1. Remove the air cleaner intake duct.
2. Partially drain the cooling system.
3. Use the J38185 in order to reposition the hose clamp from the thermostat housing.
4. Remove the radiator inlet hose from the thermostat housing.
5. Remove the thermostat housing bolts.

pic 2

6. Remove the thermostat housing.

pic 3

7. Remove the thermostat.
8. Clean and inspect the thermostat housing gasket mating surfaces.

Installation Procedure

pic 4

1. Install the thermostat.

pic 5

2. Install the thermostat housing.

pic 6

3. Notice: Refer to Fastener Notice in Service Precautions.

Install the thermostat housing bolts.
Tighten the bolts to 25 Nm (18 ft. lbs.).
4. Install the radiator inlet hose to the thermostat housing.
5. Use the J38185 in order to reposition and install the hose clamp to the thermostat housing.
6. Install the air cleaner intake duct.
7. Fill the cooling system.

________________________

When you refill the system, here are the directions for bleeding the air from the cooling system. Again, the attached pics correlate with the directions.

Fill Procedure

1. Notice: The procedure below must be followed. Improper coolant level could result in a low or high coolant level condition, causing engine damage.

Install the engine block left coolant drain plug.
2. Close the radiator drain plug.
3. Lower the vehicle.
4. Vehicle should be level.

pic 7

5. Add a mixture of 50/50 DEX-COOL(R) antifreeze and clean drinkable water until the level stabilizes at the weld seam on the surge tank.

pic 8

6. Unscrew the coolant bleed screw on the engine until coolant comes out of the bleed screw.
7. Close the bleed screw.
8. Add coolant until the level stabilizes at the weld seam on the surge tank.

pic 9

9. Install the surge tank cap.

10. Important: DO NOT exceed 2,200 RPM.

Start the engine and run at 2,000 RPM until the engine cooling fans turn ON.
11. Remove the surge tank cap.
12. Refill to the weld seam on the surge tank.

13. Important: Coolant should be at the full cold mark when the system cools.

Install the surge tank cap.
14. Inspect the concentration of the engine coolant using J26568.
15. Rinse away any excess coolant from the engine and the engine compartment.

_____________________

Make sure if the vehicle still has the original DexCool coolant not to mix it with the traditional Green coolant. Either use DexCool or look for a universal coolant that can be used with DexCool.

I hope this helps. Let me know if you have other questions.

Take care,
Joe
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Monday, November 9th, 2020 AT 7:53 PM
Tiny
ALEXTTT
  • MEMBER
Thank you for replying back. Also I been using 100% Dex-cool concentrated. What are some problems I have encounter if I don t add water to the concentrated antifreeze?
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Monday, November 9th, 2020 AT 8:49 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

It won't cause any problems. However, when you use a 50/50 mix, it actually makes the coolant stronger. For example, it will lower the freezing point as well as raise the boiling point. I don't know where you live or if that is even a concern for you.

Let me know if you have other questions or need help.

Take care,
Joe
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Monday, November 9th, 2020 AT 9:07 PM
Tiny
ALEXTTT
  • MEMBER
That s good to know. Also the heater takes at least 20 minutes to work. But I m sure that s cause of the thermostat.
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Monday, November 9th, 2020 AT 9:47 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

In most cases, that will cause the heater to be less effective. If you can, let me know how it turns out for you.

If you have questions, feel free to ask.

Take care,
Joe
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Tuesday, November 10th, 2020 AT 12:21 PM
Tiny
ALEXTTT
  • MEMBER
So during this process I disconnected the battery cause a evap code came on for the canister purge valve so now the it s ticking a lot. So I disconnected the battery and now it won t start all lights turn in radio is good. I went to AutoZone and had the battery tested and it s good. I believe the starter maybe be bad. I was reading a forum where the starter goes bad over time because the exhaust pipe is so close to the starter.
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Tuesday, November 10th, 2020 AT 12:49 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Do me a favor. Have a helper turn the key to the start position while you record what is happening under the hood. Also, take a look through this link and let me know if it helps. I doubt the starter went bad, but anything is possible.

https://www.2carpros.com/articles/starter-not-working-repair

Make sure the battery terminals are clean and tight and confirm a fuse didn't blow when you disconnected the battery. Also, make sure it is fully in park or neutral when trying to start it.

See the attached pics to help locate the fuses I need checked. In addition to checking the fuses' conditions, make sure there is power to them and out from them. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know what you find.

Joe
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Tuesday, November 10th, 2020 AT 1:04 PM
Tiny
ALEXTTT
  • MEMBER
I ll check those. Also on my radio it says locked. I figure it has to do something with the anti lock system.
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Tuesday, November 10th, 2020 AT 2:26 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The radio is locked? That could be due to disconnecting the battery.

Have you had success in locating the issues?

Joe
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Wednesday, November 11th, 2020 AT 2:05 PM
Tiny
ALEXTTT
  • MEMBER
I had it towed to the dealership and they said the battery has low voltage, so they are going to replace the battery. I find it weird before I took the battery out it started up fine and then once I reconnected it the battery wouldn t allow it to start.
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Wednesday, November 11th, 2020 AT 2:52 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

That is odd. Actually, it doesn't make sense.

If you can, please let me know what they tell you. Also, if you have questions or need help, let me know.

Take care,
Joe
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Wednesday, November 11th, 2020 AT 2:54 PM
Tiny
ALEXTTT
  • MEMBER
Alright, so I got the car back and it s running a lot better. Changing the thermostat fixed my P0128 problem.
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Thursday, November 12th, 2020 AT 3:39 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Thanks for letting me know. It's crazy anymore the things that cause problems. Who would think the engine has a predetermined amount of time it must warm up within. LOL

Take good care of yourself and please feel free to come back anytime you have questions in the future. You are always welcome here.

Joe
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Thursday, November 12th, 2020 AT 6:46 PM

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