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Couple Questions Thermostat/Sensor


Well-Known Member
December 17, 2011
Reaction score
City, State
Lazear Co
Year, Model & Trim Level
1997 Explorer 5.0
What is the stock Thermostat? 195? Also I have code P0117 Coolant Temp Sensor/ Low. I unplug the single wire sensor and plug it back in and I can get rid of the code. Thing is the truck runs badly and sputters until it warms up some then the Code comes back on and the truck runs good again. Slight miss with the code. But much better then the code being gone.

I noticed I have a reading on the temp gauge that in my best guest reads around 160 Degrees. I also noticed I have some coolant below the thermostat,looks like it has been there for a while. Could the PO put in the wrong thermostat and that is what causes the Code P0117? I read this and it seems it could be the Thermostat.

By the way this is the sensor that talks to the PCM and not the one that shows you your engine temp.

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T-stats come in all kinds of temperatures, so yes all it takes to put in the wrong one is for someone to do it.

The single wire sensor is the dash gauge sensor. Not sure why the CEL should go out by disconnecting that, since IIRC the ECU uses data from the two wire sensor.

Anyway, the sensors are $5-$10 each at Amazon or Rockauto, so I'd just replace them as a matter of course. The T-stat is about the same price so I'd just replace that too.

Here's a thread about it:

I had a shop replace one of the sensors to get the gauge in the truck to work. He replaced the single wire sensor and it never fixed the gauge. I then bought the other sensor and installed it my self. That fixed the gauge in the truck. That was the 2 wire sensor. I have read both the single wire sensor is the dash gauge and the two wire sensor is the dash gauge. All I know is when I replaced the 2 wire sensor it fixed the dash gauge. This was the one under the Coil pack in the middle. I am planing on replacing the Thermostat and I will also replace the single wire sensor again in case it was bad out of the box.

OK,just went out and unplugged the sigle wire connecter. The dash gauge did not work so your right. Here is what I think happened. I replaced the 2 wire connector /sensor with the wrong sensor. I must have put in the dash gauge sensor in that spot in the middle of the coil packs. So when I put that in only one wire was doing anything. Is that possible to put in the wrong sensor in the first place? One is called Coolant Temp sensor and the other is called Temperature sensor.

You might have a wiring issue. The single wire is definitely the gauge sender, while the double wire is the sensor used by the computer. Could be that you have a bad wire or connection and just by messing around in there, you restored the connection.

One last question.
Is the Coolant Temperature Sensor and the Temp Sender both the same sensor,which is interchangeable? I only see one listed on Rock auto and that is the Temp Sender. It is called the Temp Sender/Sensor. At least one of them is listed as the Coolant Temp Sensor.

One last question.
Is the Coolant Temperature Sensor and the Temp Sender both the same sensor,which is interchangeable? I only see one listed on Rock auto and that is the Temp Sender. It is called the Temp Sender/Sensor. At least one of them is listed as the Coolant Temp Sensor.

Ya, I see that too for your truck. It's listed pretty much everywhere as a combo. Odd. Here's a sensor diagram for your truck, which shows two sensors (one for the gauge, one of the computer)

But all the parts sites list it as you describe it: sender/sensor. If it were me, I'd pull the single wire sensor. If the passageway you pull it from is full of coolant, then you know the parts sites are full of crap. Then you can take it to Autozone or whatever and match it up to a 97 or 99 sender or w/e.

Ya I know where they both are now(single vs double wire) but I am sure both of them are the same Sensor/Sender. I guess the wire/wires to each just go to different areas. One to the gauge and one to the computer. I will just have the Thermostat changed out for now and see if that solves anything. I really think it is a 160 Degree one and that would give the code for low temp from the Sensor(2 wire).

How can the two devices (one sender and one sensor) be the same if one has one wire and the other two wires?? I also have a '97 5.0 and they are definitely different. The two wire "sensor" connects to the PCM on one side (light green/red wire)and a common sensor ground (grey/red wire). The one wire "sender" has a red/white wire to the gauge; ground is picked up thru the thermosate housing it mounts in. Based on your original problem description, I think your problem is the "sensor" - the hard starting happens because the PCM thinks the engine is warm when it's really cold. Good luck.

Both of the sensors have 2 prongs. On the single wire sensor the plug only has one wire going in but it still has 2 prongs. It is the wires that connect to them go to different areas, one to the dash gauge and the other to the PCM.
They are both just sensing what is going on and then sending that info to different areas.

Pull your Dash gauge(single wire) and look at the sensor. It has 2 prongs.

The two prong goes to PCM, it is a more precise thermistor.
The one prong goes to the dashboard gauge, and it gets the circuit continuity via car ground. Some cars have plastic manifolds for those sensors, therefore grounding needs to be done by a prong/wire too (so it will use two prongs).

This is a single prong sensor for gauge (note the flat tip too) that doesn't work in plastic housing (of a 4.0L V6 SOHC):

This is the plastic SOHC housing with two sensors.

Neither one of my sensors looked like that and I don't have the plastic housing. I did call CarQuest yesterday and they have 2 different Parts numbers for the 2 sensors. After looking at Rock Auto again I see they have 2 different part numbers but both are listed under Sender/sensor. I will be out today and buy a new Thermostat and Coolant temp Sensor. Hopefully between the two of them I will get rid of the P0117 Code and the slight miss in the truck. Oh and I will get a new Purge Solenoid and hose for it to get rid of the P0443 Code I have as well.

Maybe somebody replaced it and now you have the incorrect sensor?

Maybe somebody replaced it and now you have the incorrect sensor?
OH I am now sure I have the wrong sensor. here is what happened. I had a shop put in the gauge sensor and it never worked. So I did the mistake in thinking he put in the wrong sensor. I went to the Autoparts store and told them I needed the Gauge sensor. They sold it to me and I had a friend put it in the Coolant temp Sensor spot. SO I now have 2 of the Gauge sensors in my truck. That is why I have a miss and hard start sometimes. The gauge started working when he put in the other sensor but I think it was because we must have giggled the wire some how to get it to work. Sometimes it takes me a while to remember things in order but now I know. I also remember getting the hard start the very same day we changed the sensor out. Thanks for everyone's help. If my memory was a little better I wouldn't have needed any help. And I also assumed the shop put in the wrong sensor. And we all know what assuming does.:eek:

Fixed it!

Changed out the Coolant Temp Sensor, the correct one this time and I no longer have a misfire nor hard starting problem. Now on to the Purge Solenoid for the Vacuum canister.

Great that you come back to report what was the issue!

Maybe somebody replaced it and now you have the incorrect sensor?
Ha ha ha. Someone did replace it with the wrong one. ME the first time around.