Check engine light on, thermostat not working properly

Tiny
SIMPHERDY
  • MEMBER
  • 2006 CHRYSLER TOWN AND COUNTRY
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 166,000 MILES
Temperature gauge shows 1/4 warm. ECM check shows coolant temperature 172. Check engine light came on. ECM check shows thermostat too cold. Replaced x2 thermostat with a OEM 195, temperature sensor replaced, radiator cap replaced, radiator flushed. New gold color 50/50 antifreeze replaced.
Got any ideas? Thanks, I’m advance.
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Thursday, October 14th, 2021 AT 5:18 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The vehicle isn't reaching operating temperature within a predetermined amount of time, so it becomes an emission issue and sets a code. Is the code you are getting a P0128? Let me know that.

Now, here is the issue. The temperature sensor is signaling a certain temperature. We need to determine if what the PCM is receiving is correct. By chance, do you have an infrared thermometer? If you do, with the engine cold, remove the radiator cap, start the engine, and allow it to reach operating temperature. Next, using an infrared thermometer, check the temperature of the coolant being circulated in the radiator.

The most common causes are the things you already addressed, so there could be an issue with the wiring. Also, make sure the cooling fans are not turning on.

Let me know. Also, let me know if I have the correct code and if there are any others stored.

Take care,

Joe
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Thursday, October 14th, 2021 AT 7:54 PM
Tiny
SIMPHERDY
  • MEMBER
After I did all the work, I got the check engine light twice. Cleared the code and so far, it hasn t come back on. I know it s still running cool because the dash gauge is still showing the same. I must drive if tomorrow and hopefully it ll give me a code. I ll pay close attention to it this time. I do have an infrared temperature gauge so I will check the water with that after it warms up. I ll try to keep track when the fans activate. I ll be in touch. Thanks.
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Thursday, October 14th, 2021 AT 8:56 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Happy to help. Let me know what you find. Also, if you can think of anything that could help diagnose the issue, let me know. It's important that you take notice if the cooling fans are coming on early. That could be causing an issue. However, if the thermostat stays closed, it should still warm up to operating temperature.

Hang in there. We'll get it figured out.

Take care,

Joe
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Thursday, October 14th, 2021 AT 9:04 PM
Tiny
SIMPHERDY
  • MEMBER
Went 130 miles and check engine light never came on. The temperature gauge never went to half. Stayed pretty close to 1/4. When I got home, I removed the radiator cap with the pressure release type cap. Iasered the water. 215 and visibly boiling. The temperature gauge just barely above 1/4.
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Friday, October 15th, 2021 AT 11:44 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Then the sensor isn't working properly. If it was boiling, then it certainly was over 212F. I have a feeling it's a wiring issue.

Since the sensor is new, I suspect we have a corrosion issue to contend with. The signal to the gauge/computer is basically based on the amount of voltage allowed to pass through the sensor. The voltage changes a caused by temperature. If there is excessive resistance (due to corrosion or a connection), it will cause the signal to be off.

Here is what I suggest: First, disconnect the connector at the sensor. There will be two wires on the connector, one is violet with an orange tracer and the other is dark blue with a dark green tracer.

The dk blue/ dark green wire provides a ground for the sensor. Check for continuity to ground. While checking it, move that wire around to see if there is a change in resistance.

Next, with the key on, check the other wire violet/orange wire for power. Let me know what voltage is found.

This is where to start. At this point, I have a theory related to the integrated power module but don't want to jump to conclusions. In addition to checking the wiring, inspect the connector. Make sure there is no corrosion, and the connector pins are not pushed back or damaged in any way.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know if you are comfortable performing the tests or if you have other questions.

Take care,

Joe

See pic below.
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Saturday, October 16th, 2021 AT 8:08 PM
Tiny
SIMPHERDY
  • MEMBER
Haven t had a chance to check the ohms yet but I did find the connector to the sensor had the locking mechanism on it broke so I got a new connector. Just need to wire it in. Got a code.
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Sunday, October 24th, 2021 AT 10:07 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If you got a direct replacement connector, you should be able to just use the lock mechanism on yours. That way you won't have to cut anything.

I noticed you mentioned a code. What code did you get?

Joe
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Sunday, October 24th, 2021 AT 6:05 PM
Tiny
SIMPHERDY
  • MEMBER
PO128.
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Sunday, October 24th, 2021 AT 10:53 PM
Tiny
SIMPHERDY
  • MEMBER
See attached photo.
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Sunday, October 24th, 2021 AT 10:54 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Yep, that code indicates the vehicle isn't reaching operating temperature fast enough or not at all. Let me know what is found with the wiring testing.

Take care,

Joe
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Monday, October 25th, 2021 AT 5:53 PM

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