Engine temperature sensor?

Tiny
BOBZWGN
  • MEMBER
  • 1999 FORD F-150
I need to replace the cooling temp. Sensor for the gauge. All the repair books and manuals show it in the manifold right behind the thermostat housing, but its not there. I have had 3 mechanics look for it and they cant find it either. Any idea where it is?
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Friday, March 12th, 2010 AT 9:47 PM

32 Replies

Tiny
BLUELIGHTNIN6
  • EXPERT
Your vehicle uses a cylinder head temperature (CHT) sensor and it should be on the top front of the engine or maybe left side of engine if for the 4.2L engine.

Here is a guide to help you see what you are in for when changing it out.

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

Check out the diagrams (Below)

Please let us know if you need anything else to get the problem fixed.

Cheers
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Friday, March 12th, 2010 AT 10:17 PM
Tiny
SPEN89
  • MEMBER
  • 1998 FORD F-150
  • 5.4L
  • V8
  • 2WD
  • AUTOMATIC
  • 187,000 MILES
Hello, I just changed the coolant tube under the intake and spark plugs and coil packs. When I finished reassembling it, the coolant temperature gauge immediately pegged to the hot position. I changed the coolant sensor in the intake manifold and now the coolant temperature gauge doesn't move off of the cold position. I put another new sensor in and the results are the same. I have been driving the truck, and it is not overheating. Does anyone have any ideas?
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good morning,

The signal for the gauge comes from the sensor to the ECM and then to the dash gauge.

I would remove the connector and test for 5 volts to the sensor and also check the return voltage as well.

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

Based on what you have done, it sounds like you may have pinched the harness when installing the intake. Look at the back of the intake and make sure the harness is free and not damaged.

https://www.2carpros.com/articles/how-a-coolant-temperature-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-coolant-temperature-sensor

Roy

The Cylinder Head Temperature (CHT) sensor:
is mounted into the wall of the cylinder head and is not connected to any coolant passages.
sends a signal to the powertrain control module indicating the cylinder head temperature.
if the temperature exceeds 126 C (-258 F), the powertrain control module disables four fuel injectors at a time. The powertrain control module will alternate which four injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine.
if the temperature exceeds 154 C (310 F), the powertrain control module disables all of the fuel injectors until the engine temperature drops below 154 C (310 F).
DTCs are set.
If the engine reaches critical temperature, the following happens:
The coolant temperature gauge pointer will read fully hot at 121 C (250 F).
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
SPEN89
  • MEMBER
ASEMASTER6371, thank you for the help. I will check the wire loom this evening. One thing I did not mention is that I can unplug the new coolant sensor and plug the old coolant sensor back in and the coolant gauge immediately pegs to the hot location. When I unplug the old sensor the coolant gauge falls to the cold reading. When I plug the new sensor in again, the coolant gauge stays on the cold reading and never moves.
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Okay, check you wiring and let me know what you find.

Roy
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
SPEN89
  • MEMBER
ASEMASTER6371, from a preliminary check I did not see where the wire loom is pinched. I checked for power at the plug, and it basically non existent. I then used a test light to check for power and when I check one side of the plug the coolant gauge pegs to hot. The other wire does nothing.
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
FREDSRAIDERS
  • MEMBER
  • 1997 FORD F-150
  • 4.6L
  • V6
  • 4WD
  • 170,000 MILES
I have replaced the thermostat, temperature sensor and radiator due to a bad leak. But my temperature gague goes up to hot as soon as I turn the truck on. What is my possible problem? Or solution?
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
The wire to the coolant temperature sensor is grounded. That's a red / white wire. There should also be a diagnostic fault code set in the Engine Computer related to "Coolant temperature sensor voltage too low". On most vehicles that code will also turn on the Check Engine light.
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
You should have 5 volts to the sensor.

You need to put the red lead in one terminal and the black lead in the other terminal.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Do that with your voltmeter and tell me the reading.

Roy
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
SPEN89
  • MEMBER
Acemaster6371, I have 13.4 volts at the plug going to the sensor with the engine is running. When it the engine is not running it has 10.9 volts at the plug.
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Sensors should only have 5 volts.

I think somewhere the harness is shorted to power.

Roy
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
SPEN89
  • MEMBER
ASEMASTER6371, if I was shorted to power, shouldn't I be affecting what ever I am shorted with? Like blowing a fuse somewhere?
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Not in the engine harness to the ECM. There is no fuse in that circuit as the ECM controls all the grounds or returns. The ECM can handle a short to power.

Roy
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Tuesday, August 4th, 2020 AT 5:09 PM (Merged)
Tiny
JJURIGA27
  • MEMBER
  • 1995 FORD F-150
Engine Cooling problem 6 cyl Two Wheel Drive Automatic 185000 miles

I bought a new swith today form NAPA, and am having trouble finding it. Any ideas? I have the Haynes book, it says right rear corner of engine block, just below cylinder head. Only problem is that I dont know if by right side, they mean when youre sitting in it, or outside looking at it. I also do not really know what the cylinder head is.

HELP!
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Tuesday, August 4th, 2020 AT 5:10 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Hello,

The coolant temperature sensor is located near the front of the engine for both 6 and 8 cylinder engines. Here is a guide to help you see what you are in for when doing the job

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

Here is the engine coolant sensor location for both engine (below)

Let us know what happens and please upload pictures or videos of the problem.

Cheers
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Tuesday, August 4th, 2020 AT 5:10 PM (Merged)
Tiny
JJURIGA27
  • MEMBER
Got it done! Thanks. It took a little bit, and I found out that the coolant will begin to leak out, but its done! I love this site
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Tuesday, August 4th, 2020 AT 5:10 PM (Merged)
Tiny
RAY454
  • MEMBER
  • 1997 FORD F-150
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 268,000 MILES
Where is the engine coolant temp sensor located on 4.2 v6 1997 ford pickup
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Tuesday, August 4th, 2020 AT 5:10 PM (Merged)
Tiny
OBXAUTOMEDIC
  • EXPERT
Hello,

It is usually located around the thermostat housing. Just follow the top radiator hose.

.
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Tuesday, August 4th, 2020 AT 5:10 PM (Merged)
Tiny
SUWLF
  • MEMBER
  • 1995 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
What is the housing called that the coolant sensor is fastened into? My truck has the 5.8l engine. The thermostat housing is on the front of the engine. This is on the top just above it. It houses the coolant temperature sensor and two tubes for coolant coming out of it (the sensor screws/fastens into it has a connector wire running to it) it is octagon in shape and has two tubes brazed into it. Also, one tube about ten inches in length goes into a heater core hose, the other smaller tube and hose goes to the throttle body base. I have a ford parts# its, number 18B402 off of a 1995 Ford 5.8l diagram, cannot seem to locate this part anywhere. No one knows what it is called and when I go to a parts warehouse the number off the diagram comes back as a AC/Delco brake drum. Thanks for the help.
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Tuesday, August 4th, 2020 AT 5:11 PM (Merged)
Tiny
DOCFIXIT
  • EXPERT
Are there two wires connected one white/light blue other red?
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Tuesday, August 4th, 2020 AT 5:11 PM (Merged)

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