Where is the Engine Coolant Temperature Sensor located?

Hello, So Ford has these Coolant Temperature and Cylinder Temperature Sensors listed a bit strange.
The first two diagrams are for the Coolant Temperature Sensor. You'll be able to find easiest by the wire coloring. It's two wires with light green/red and grey/red wire colors.
The Cylinder head Temperature sensor you'll also have to go by wire coloring, because it's listed in 2 different places depending on how many valves the engine has, but it's always easiest to find sensors by wire colors. It also two wires, grey/red and yellow/light green. its either on the front of the engine or on the complete opposite side, on the back.
Are you getting codes for these Sensors?
Also, on some vehicles the Cylinder Head Temperature sensor is used instead of a coolant Temperature Sensor. So, it depends on what type of set up your vehicle has.
While looking up the Coolant Temperature sensor for this vehicle, it was actually listed under the Air Condition section, which is strange, but that's how I was able to find that particular sensor.
So, you may find one or the other, or both sensors.

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

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

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

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

Yes, I'm getting codes for both. First check engine light came, got code for engine coolant sensor so I had it replaced. Check engine light never went out and couple days later coolant light came on, had it checked showed code for Engine Cylinder Temperature Sensor and Coolant Temperature Sensor. AutoZone sold me a ECT sensor, but it looks nothing like part Ford shows. And two Ford mechanics say there's only one sensor, not two. I'm so confused. But thank you for your help.

Well, take a look in those locations for those wire colorings, they're a 2-wire sensor.
It may have both, not every technician knows everything. If you are getting codes for both, the ECM is seeing something. The Ford OEM parts may look different from aftermarket parts from AutoZone. The wiring diagrams are a bit different, and everything is not always straight forward. Make sure your coolant level is full, just never open the radiator when it's hot.
If you really can't find the correct sensor and you're still getting two codes like that, call the dealership and ask their parts department why this is happening and if it's possible for the vehicle to have both. Hope this helps, let us know how you make out.

I’ll definitely give it a try. Thank you

No problem, if you need any other help or wiring diagrams let us know, we have about 33 Technicians here so I will put an inquiry into them about the issue and see what if they have any more information on the matter. Will repost here in a day or so.

That would be great. And I’ll keep you posted on any progress.

Hi,

I noticed it has been several days since we heard from you. Has any progress been made? We're interested in knowing.

Let us know if we can help.

Joe

Not really. Weathers been pretty rough, work hours long so maybe Saturday.

Sounds good. Feel free to let us know if there is anything we can do to help.

Take care,

Joe

Hello,

Have you been able to locate both of these sensors, or one or the other? I know on my ford ranger the coolant temperature sensor is in the front of the engine, more like this picture below. But I think trying to trace the wire coloring will be your best bet. I'm not sure why Ford techs would tell you it doesn't have both, if you're getting both codes. Another possibility I thought of was maybe the Engine computer (ECM) needs a software update. There always seems to be an update for software on many different vehicles. Sorry, this is such a confusing issue, I have read others saying the same thing, that Ford uses Cylinder Head Temperature sensors instead of coolant sensors. I was curious if you remember what the exact Codes numbers were, such as P followed by a number. If we have the code numbers, I can look up exactly what the criteria is for setting either one of these codes. I'm wondering also is this the Expedition "EL" model? And do you have Automatic A/C climate controls? Where you can adjust the temperature for both the passenger and driver side differently? The code numbers would really help, i would like to find out how it's outputting both codes.

I never found the Engine Temperature Sensor. Changed the Engine Coolant Temperature Sensor. Will have to go back and get codes. It's crazy because the truck never runs hot. But with temperature sensor on it while driving at up to 190 its fine. At 192 degrees the fan starts going on and off. And the temperature gauge falls from right before half, which is where it normally stays while driving down to cold and back up again. I'm at a loss.

The gauge falls all the way back down to cold while driving? Is the check engine light on? Maybe you just need a new thermostat. If they get stuck partially open, it will do that, it happens all the time. Sometimes they will still be opening and closing the way they're supposed to, just not fully closing all the way. They are pretty cheap too; I will see if I can find a diagram showing its location. Al you'll need is a thermostat and a couple gallons of 50/50 coolant, Ford probably has their own type of coolant like everyone else these days. But the thermostat is usually around $20.00.
Okay, below I posted a picture of the Thermostat, and it does require Ford coolant, I'm not sure what you have been putting in so far.

It's the 4x4 Limited. And I thought thermostat from beginning but was going by codes. I’ll definitely change that out this week and see if it helps. Thank you so very much for the information.

And yes, check engine light is on.

so, you have codes stored in the ECM, write them down this time so we have the exact numbers, because there can be a couple codes for one sensor depending on if it's a circuit problem, ie electrical or something else.

Okay, will do.

P0128 and P0119.

Hi,

If I hope you guys don't mind if I jump back in with you.

I looked at both of the codes that the vehicle as it is a simple issue. The engine is not reaching operating temperature within a specified amount of time. In other words, it's taking too long to warm up.

In most cases, this is caused by a faulty thermostat or temperature sensor. This is where the confusion comes into play.

Some of these vehicles came with only a cylinder head temperature sensor and others came with both a cylinder head temperature sensor and coolant temperature sensor. The only want to determine which you have is to check for the coolant temperature sensor. If it has one, it will be tucked behind the alternator and mounted in the engine block. However, most only came with a cylinder head temperature sensor, which can set the code P0119. See pic 1 below.

See pic 2 for code P0128. As far as the P0128, here is what I suggest: Using an infrared thermometer for cars, check to see if the engine coolant at the radiator reaches at least 195 degrees F. If it doesn't or takes a long time to do it, replace the thermostat. If it does reach temperature within approximately five minutes, then suspect it is one of the sensors.

Let us know what is found. If it requires the sensor to be replaced, we will then determine which one you have or if you have both.

Take care,

Joe

See pics below.

I'm going to replace the thermostat and see if that fixes it as I've already changed the ECT sensor, twice. (Could never locate CHT sensor.) Thank you and I’ll update ASAP.

Hi,

If does have a CHT sensor, it will either be in the rear of the cylinder head (right bank) or under the intake toward the front left.

Based on the codes, I think replacing the thermostat is a good idea. Hopefully, that will take care of your problems.

Take care and let us know.

Joe

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.

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.

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.

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

Okay, I’ll try that. CTS still have to locate and change. Thanks for the diagrams, they’ve helped so much. Thank you

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.

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.

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.

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

This is for KAM reset from All Data.

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?

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?

Good evening, do you think the attached info is correct?

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?

Tried that reset. Was clear for about 10 miles. It's the 3 valve but here's VIN #1FMFU20588LA31704.

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.

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.

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.

I have only noticed it when I'm going straight.

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.