Where is the Engine Coolant Temperature Sensor located?

Tiny
OL LADYL
  • MEMBER
Well, the issue may be that I've replaced the CHT sensor with the ETC sensor because I did replace the one under the intake etc. I'm going to put thermostat in early in the morning. Hoping that ll do it. Thanks for all the advice as I'm a lady struggling solo to get it done.
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Monday, November 15th, 2021 AT 7:37 PM
Tiny
JOE F
  • EXPERT
You are very welcome. Listen, we are here to help you any way we can, so please let us know what we can do to help.

I attached two pics below. The first is the cylinder head temperature sensor and the second is the engine coolant temperature sensor. Maybe the pics will help you identify what was used.

Take care, and again, feel free to let us know if we can help.

Joe

See pics below.
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Monday, November 15th, 2021 AT 9:00 PM
Tiny
OL LADYL
  • MEMBER
Hi guys, changed thermostat no changes with the exception of temperature gauge fluctuating. I replaced the CHT sensor. So, I guess my next move will be to change the ECT sensor. Still getting codes PO 119 and PO 1289.
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Tuesday, November 16th, 2021 AT 11:05 AM
Tiny
AL W
  • EXPERT
Were you able to find the coolant temperature sensor? and before you change it, do one thing, unplug the cylinder head temperature sensor, and with the key on check the cylinder head temperature sensor for 5 volts on the blue/grey wire. If you have a multimeter available. and is that other code p01289? it should only be 4 numbers i believe..

https://www.2carpros.com/articles/how-to-use-a-voltmeter
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Tuesday, November 16th, 2021 AT 11:17 AM
Tiny
OL LADYL
  • MEMBER
Okay, I ll try that. CTS still have to locate and change. Thanks for the diagrams, they ve helped so much. Thank you
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Tuesday, November 16th, 2021 AT 11:48 AM
Tiny
AL W
  • EXPERT
This is the criteria for code setting of P0128. If that 5 volts at the cylinder head temperature sensor is low or missing, Thats a big concern.
Looking on All Data now I do not see a coolant temperature sensor, so I think these codes are setting due to a calibrated range not being met, as you'll see below, there are a few different things the ECM looks at, and if the vehicle doesn't warm up in this time frame, this P0128 will set. So, this may not be a thermostat or Cylinder head Temperature sensor issue. Take a look at the Thermostat Monitor below and you'll get a better idea of what the ECM is expecting to see, and for whatever reason it's not meeting this criteria. So, we have to figure out why it's not warming up in the time allotted, or another sensor may be reading incorrectly.
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Tuesday, November 16th, 2021 AT 1:16 PM
Tiny
OL LADYL
  • MEMBER
I think that at this point I'm going to put it in the shop. Ford gave me an estimate of $675.00 to replace both sensors. I really don't want to spend that, but I have to have transportation. Will post updates ASAP. Have a wonderful evening.
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Tuesday, November 16th, 2021 AT 1:26 PM
Tiny
AL W
  • EXPERT
Thats a lot of money, I've gone through all the wiring diagrams on ProDemand and All Data and don't see both sensors. You might want to try resetting the ECM before having them change more parts, the ECM needs time to relearn the new Temperature Sensor. You can try disconnecting the battery negative for 5 minutes and it will clear out the Keep Alive Memory, this should always be done after replacing a new sensor anyway.
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Tuesday, November 16th, 2021 AT 1:31 PM
Tiny
OL LADYL
  • MEMBER
You are 100% right about that, but I'm at the end of my rope. If there's only one sensor figuring out which one it has escapes me. I will look into ECM reset ASAP. Never even thought of that. Thanks
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Tuesday, November 16th, 2021 AT 1:35 PM
Tiny
AL W
  • EXPERT
This is for KAM reset from All Data.
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Tuesday, November 16th, 2021 AT 1:41 PM
Tiny
OL LADYL
  • MEMBER
Hi guys, I'm back with a question. It's entirely possible that I put CHT sensor where ECT sensor goes. Could this possibly be the problem?
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Wednesday, November 17th, 2021 AT 2:03 PM
Tiny
AL W
  • EXPERT
Looking up info right now for you,
This is the Ford part number for the CHT sensor and pic1 9L8Z6G004C
This is the coolant temperature sensor part number 4L3Z12A648AB
They both look similar. I will keep looking for more info
If you look at these codes too, they don't really refer to two different sensors,
The p0119 refers to a circuit problem, and if there's a wiring issue, which means the ECM is getting an incorrect reading, this is leading to the p0128 code. Thats why I was wondering if the CHT had five volts on one wire while unplugged. It doesn't say coolant sensor, its saying that Temp sensor circuit has an issue. I don't think your vehicle has both sensors, I haven't found any diagram that lists both sensors.

I've been looking in numerous places for 3 days now and have not seen one with both sensors. This P0119 says that the circuit intermittently became open or shorted while the vehicle was running. Thats what set this code. So, if there's a contact point where the harness is rubbing threw and touched ground for a second, it will set this code. Engine vibrations cause this type of thing. Checking contact points of the harness is usually how these type errors are found.

I'm reading this can be caused by trapped air in the coolant system as well.
It is also possible that they gave you the wrong part, and you put a ETC sensor in where a CHT sensor goes. Did you go to AutoZone or an aftermarket parts store?
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Wednesday, November 17th, 2021 AT 3:08 PM
Tiny
OL LADYL
  • MEMBER
Good evening, do you think the attached info is correct?
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Thursday, November 18th, 2021 AT 3:33 PM
Tiny
AL W
  • EXPERT
I have read this too, depending on how many valves the engine has. So it depends on which engine you have. I read there was a 2 or 4 valve engine, and this is talking about the 3 valve engine. So its hard to tell which information is correct. Can you give me the Vin Number of your truck and I can try looking it up by that.
And what are its symptoms at this point? Did resetting the ECM not help any?
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Thursday, November 18th, 2021 AT 3:53 PM
Tiny
OL LADYL
  • MEMBER
Tried that reset. Was clear for about 10 miles. It's the 3 valve but here's VIN #1FMFU20588LA31704.
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Thursday, November 18th, 2021 AT 4:09 PM
Tiny
AL W
  • EXPERT
So you're still getting both codes back? And were these the wire colors of the Sensor you changed? And what is the Temp gauge doing now? Is it still jumping up and down to cold or what exactly is happening now? I'm still looking at this Thermostat Monitor system.

Also, I was wondering did you put a 195f degree thermostat in the truck? This P0128 is related to the engine not reaching operating temperature in a set amount of time or being within 20f degrees of the thermostat operating temperature. It's saying the monitor runs each drive cycle and runs from 5-13 minutes. It looks at the Intake air temperature sensor if after a 2-hour soak time (so engine off after driving time) if the engine temperature is not where it should be after that 2 hour.
I know this sounds confusing, but really the ECM is just looking to see that the engine is warming up fast enough. And then we have the p0119 which is saying a circuit issue happened.
So, I would investigate the CHT sensor circuit some more. Even if the connector to it or a connector down the line is corroded or a wire is rubbing on a contact point on the engine or frame, it can trip this p0119, that in turn will look incorrect to the ECM and trip the p0128.
If you follow the harness from the CHT sensor and check each spot that the harness makes a turn or can rub on a bracket or the frame, you may find a bad spot. You can do a wiggle test too while the engine is running, wiggle the harness is if the engine running condition changes or stumbles, the you're in the right area.
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Thursday, November 18th, 2021 AT 4:34 PM
Tiny
OL LADYL
  • MEMBER
Yes, I put the 195-degree thermostat in it. It's still falling down to cold, temperature light comes on for a second or two, temperature goes back to normal and the light goes out.
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Thursday, November 18th, 2021 AT 5:02 PM
Tiny
AL W
  • EXPERT
Okay, so let me see what criteria it takes for the light to come on, and what exactly controls the gauge.

When exactly is this happening? Is it during hard acceleration or just sitting idling? Turning certain directions? Right, left? Any other details?

Okay, so I want you to do this test (pic1). The Temp Gauge is not operated by the CHT sensor. The instrument cluster gets its information on the CANbus Network. This means this may be an issue with the Instrument Cluster, a CANbus network that is losing communication temporarily, the reason you may not be getting codes or any other systems, is that at AutoZone or a parts store, they probably can only scan the engine computer. There may be other codes stored in other modules like the Cluster that you're not seeing. Basic cheap scan tools only give you powertrain codes which is why they all start with a "P". The Cluster Module could have "U" codes stored in it which would mean a loss of communication.
Basically, what I'm saying this the Temperature Gauge is controlled by Data on a network, not directly from a sensor. This vehicle needs a full system scan to see if there are any other codes in other modules. A decent shop can do this for you, it won't be free but it may give you a better direction. And not cost $700.00. What if this is an Instrument Cluster failure? Try this first test and see what it tells you. You don't need a Scan tool to do it.
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Thursday, November 18th, 2021 AT 6:30 PM
Tiny
OL LADYL
  • MEMBER
I have only noticed it when I'm going straight.
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Thursday, November 18th, 2021 AT 7:14 PM
Tiny
AL W
  • EXPERT
So under a steady cruise, The thing is I don't think your engine is going cold and heating up, I think there's an issue with a wire shorting out somewhere because it doesn't seem that anything has changed since you replaced that sensor and the thermostat.
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Friday, November 19th, 2021 AT 6:42 AM

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