The temperature gauge is reading low most of the time all of a sudden?

Tiny
MHOUT
  • MEMBER
  • 2011 FORD FUSION
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 98,000 MILES
The engine also seems to be running a little rough. Other than that, everything seems normal. I should note that about two weeks ago when I had my oil changed the tech put a filter on without the gasket and blew oil all over the bottom of the motor. I'm wondering if this affected the ECT sensor. Also, there is no check engine light.
Friday, November 25th, 2022 AT 12:37 PM

7 Replies

Tiny
STEVE W.
  • MECHANIC
  • 14,504 POSTS
Not likely an issue caused by the oil as the cooling system sensor is on top of the engine between the cams and between cylinders 2 and 3. It could be a bad valve cover gasket letting oil into that area or the sensor is damaged by corrosion which is somewhat common. Replacement is simple, pop the cover off, unplug the connector and unscrew the sensor. Screw in the new one and connect it and put the cover back in place. If you find corrosion you will want to get a replacement pigtail and wire it in as cleaning usually isn't enough.
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Friday, November 25th, 2022 AT 7:24 PM
Tiny
MHOUT
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Hi Steve, thanks for the reply. Does this engine have 2 sensors? While researching the problem I’ve been getting conflicting information. Some say it’s on top and others say it’s the one under the air intake in front of the first cylinder by the oil filter. Do you also know if different engines were put in these cars? None of the videos or information I could find were about this engine. Thanks again!
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Saturday, November 26th, 2022 AT 4:47 AM
Tiny
STEVE W.
  • MECHANIC
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Single sensor up on top of the engine. Part #8S4Z6G004A Ford used both types on some applications when they used a different control for the cooling fans and gauges, then they went to the single CHT on others.
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Saturday, November 26th, 2022 AT 8:12 AM
Tiny
MHOUT
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I appreciate the response. I just picked one up and will give it a try. Thank you.
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Saturday, November 26th, 2022 AT 11:26 AM
Tiny
STEVE W.
  • MECHANIC
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I'm not a big fan of them simply due to the way they read, the thermal mass of the head or block can throw the sensor off. On the ones with both sensors, it's common to dee a 10� 15-degree difference between the coolant temperature and the head temperature. However, they can be handy, I've used them on air cooled engines to monitor the head temperatures.
One thing I forgot to mention, check the bore it goes in for corrosion as well. Aluminum oxide is a good insulator so if the bore gets corroded it can change the readings.
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Monday, November 28th, 2022 AT 4:51 AM
Tiny
MHOUT
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Hey Steve, I was able to replace that sensor this afternoon and that doesn’t seem to be the issue. I was hoping not to have to bring it to my mechanic, but I don’t know what the problem is.
Thanks.
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Monday, November 28th, 2022 AT 3:34 PM
Tiny
STEVE W.
  • MECHANIC
  • 14,504 POSTS
Okay, the symptoms are rough running, and it doesn't seem to be getting as warm as it did, what is the heat like and does it seem like it is getting up to operating temperature slower? My first thought would be a thermostat that's opening early or stuck partway open. The easiest way to tell for that would be with a non-contact thermometer and use it to check the temperatures of the hoses and engine to see if the thermostat is staying open. Normally the top hose will stay cold until the thermostat opens, if you start the engine and watch the hose temperatures you shouldn't see or feel the upper one getting hot until the thermostat opens, if instead you feel it start to warm up as the engine runs the thermostat is open.
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Monday, November 28th, 2022 AT 11:48 PM

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