• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!

Permanently overheated???

Messages
160
Likes
38
Location
Wildomar
#1
So I was cruising down the freeway and my car suddenly overheated and immediately went into limp mode where the car wouldn't rev above idle. When I popped the hood it all looked totally normal. The coolant was a little low, but not empty. I had the car towed to my apartment, and after a few hours the temperature gauge on the dash still read max temp. The next day the temperature gauge STILL read max temp. I'm assuming the coolant temperature sensor, or the cylinder head temperature sensor, or both went bad. Anybody heard of this?

Also the car starts and runs just fine, but after a few seconds starts to idle roughly, and won't rev above idle. I don't know if that natters though. I'm assuming its part of limp mode.

Any help is greatly appreciated.
 

D1JL

Administrator
Staff Member
Messages
5,774
Likes
1,746
Location
SFV, So.Cal.
#2
You are correct, a coolant sensor failure could be your problem.
If I were doing the testing I would use a sensor simulator because I have one.
The simple alternative would be to replace the sensor as they are cheep enough and go from there.
 

D1JL

Administrator
Staff Member
Messages
5,774
Likes
1,746
Location
SFV, So.Cal.
#3
BTW:
There is another easy test you can do.
If you remove the two wire connector from the coolant sensor (ECT) and then turn on the car but do not start, the gauge should go to cold.
You should now be able to start the car and it should run normal.
However, it will set a code and turn on the check engine light.

With the connector removed from the ECT you could short the two wires together and the gauge should go to full hot again.

The ECT sensor is on the driver's side of the car (USDM), on the end of the head toward the rear.
 

TyphoonFiST

4000 Post Club
Messages
4,873
Likes
1,597
Location
Rich-fizzield
#4
You are correct, a coolant sensor failure could be your problem.
If I were doing the testing I would use a sensor simulator because I have one.
The simple alternative would be to replace the sensor as they are cheep enough and go from there.
Where did you get this sensor simulator? Id like to add one for this purpose! [raceflag]
 

D1JL

Administrator
Staff Member
Messages
5,774
Likes
1,746
Location
SFV, So.Cal.
#5
Where did you get this sensor simulator? Id like to add one for this purpose! [raceflag]
As a retired professional mechanic, I purchased it years ago from one of my tool vendors.
The two I used the most were Snap-On and Matco, I am sorry I do not remember which one.
The item came in a black box and I think was made by OTC, mine I am SURE is out dated.
 

TyphoonFiST

4000 Post Club
Messages
4,873
Likes
1,597
Location
Rich-fizzield
#6
As a retired professional mechanic, I purchased it years ago from one of my tool vendors.
The two I used the most were Snap-On and Matco, I am sorry I do not remember which one.
The item came in a black box and I think was made by OTC, mine I am SURE is out dated.
If its a good tool....It can never be out dated. Ive bought tools that are a decade old that can never be replaced also due to not being made but work better than the crap that is out now. Ill check out OTC...see if I can find it! [thumb]
 

D1JL

Administrator
Staff Member
Messages
5,774
Likes
1,746
Location
SFV, So.Cal.
#7
If its a good tool....It can never be out dated. Ive bought tools that are a decade old that can never be replaced also due to not being made but work better than the crap that is out now. Ill check out OTC...see if I can find it! [thumb]
I do agree.
Mine has got to be at least 25 years old and it still works great but I doubt you could find one like mine.
I only meant that the new ones do so much more.
I am not going out to my tool box at this time but I will look for a part number later.
 

TyphoonFiST

4000 Post Club
Messages
4,873
Likes
1,597
Location
Rich-fizzield
#10
[MENTION=3563]TyphoonFiST[/MENTION]

I was wrong, the manufacturer of my sensor simulator is Products Research Inc. (PRI).

This is the unit I have.

PRI SST

As I said, mine is old and new ones may have more functions.

This one just sold on 4/1/19

PRI-SST-Sensor-Simulator-Tester-Older-Model
They are still out there! Noice....just gotta be quick on the draw !

Sent from my SM-N950U1 using Tapatalk
 


Top