Temperature gauge stays on cold

SMB985

MEMBER
2005 MERCURY MONTEREY
4.2L
6 CYL
2WD
AUTOMATIC
180,000 MILES

Our car's temperature gauge stays on cold. Not sure how long this has been since our son has been driving it. The heater and A/C both work. It does smell hot. Was not real low on coolant. Not sure where to start. Also, he called me and said it was not running right. Really rough like maybe bad plugs. I picked him up and that is when I noticed the gauge. Where would I start at?

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Friday, September 7th, 2018 AT 3:46 AM

13 Replies

DANNY L

MECHANIC
5,648 POSTS

Hello, I am Danny.

Just a quick question first. Is the Check Engine Light on? If so it would help to give us the code(s). If you do not have a scanner to check the codes you can go to you local auto parts stores (O'Reilly's, Pep Boys, AutoZone) and the will check for free. I have attached a tutorial showing what is involved. Hope this helps and hope to hear back soon. Thanks for using 2CarPros.
Danny-

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

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Friday, September 7th, 2018 AT 1:27 PM

SMB985

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6 POSTS

I ordered a scanner today. The van is running so bad that I really do not want to drive it. Is it possible that the temperature sensor can cause a head issue?

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Friday, September 7th, 2018 AT 1:32 PM

DANNY L

MECHANIC
5,648 POSTS

Hello again.

Yes, that is possible. Without knowing the code(s) it makes it difficult. Once you get the scanner tell us the codes and we will go from there. Hope to hear from you soon and again thanks for using 2CarPros.
Danny-

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Friday, September 7th, 2018 AT 3:31 PM

SMB985

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6 POSTS

Thanks.

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Friday, September 7th, 2018 AT 3:36 PM

DANNY L

MECHANIC
5,648 POSTS

You are Welcome!
Hope to hear back soon with code information and thanks again for using 2CarPros.
Danny-

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Friday, September 7th, 2018 AT 3:56 PM

SMB985

MEMBER
6 POSTS

No error codes but have emissions issues. Doing a tune-up to see if those get corrected.

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Tuesday, September 11th, 2018 AT 6:47 AM

DANNY L

MECHANIC
5,648 POSTS

Hello again.

Okay, sounds good. Let me know the outcome. I would be glad to help. Thanks again for using 2CarPros.
Danny-

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Tuesday, September 11th, 2018 AT 11:57 AM

SMB985

MEMBER
6 POSTS

So the coil pack was cracked. New pack, wires and plugs no more rough issues. The temperature gauge still does not work even with a new thermostat. No codes. How do I test the sensor for the gauge?

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Wednesday, September 19th, 2018 AT 4:32 PM

DANNY L

MECHANIC
5,648 POSTS

Hello again.

I have attached a diagram for you. You can use a volt meter to test the coolant temperature sensor. It is located on the right side of the lower intake manifold. Hope this helps and thanks again for using 2CarPros.
Danny-

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Wednesday, September 19th, 2018 AT 6:44 PM

SMB985

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6 POSTS

Thanks but unfortunately I am not able to locate the sensor. Would you happen to have a picture or diagram where it would be?

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Thursday, September 20th, 2018 AT 4:16 PM

SMB985

MEMBER
6 POSTS

Our local Library does not have a repair manual for this vehicle.

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Friday, September 21st, 2018 AT 7:26 AM

KEN L

MASTER CERTIFIED MECHANIC
42,787 POSTS

Hello, At ECT sensor harness connector. - Component Location: Right side of the lower intake manifold: Here is a guide that will help you step by step to replace it:

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Please run down this guide and report back.

Cheers, Ken

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Friday, September 21st, 2018 AT 10:24 AM