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Coolant temperature sensor or connector

Tiny
STEVEN SPELLMAN
  • MEMBER
  • 2001 KIA SPORTAGE
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 284,500 MILES
So I recently had to replace my timing belt and on this model, you have to remove the thermostat housing which also is the home of the coolant temperature sensor. The SUV will run when the connector to the coolant temperature sensor isn't connected but when it is connected it causes it not to start.

I replaced the thermostat, coolant temperature sensor, and gasket. I've replaced the coolant temperature sensor twice thinking that maybe it was a defective new part from AutoZone. I recently bought a new connector and spliced it on and still got the same results of a no start when connected. I also get the code p0117 now.

I've had my timing rechecked by a licensed mechanic thinking that may be the issue. Everything checked out fine there. I replaced the fuel pump prior to the timing belt being replaced also. It starts fine without that sensor being connected so I assume this wouldn't be the cause of the issue.

So can anyone think of any reason as to why the connector keeps the SUV from starting when it is connected? It starts up fine without the coolant temperature sensor being connected. Any help is greatly appreciated! Thank you
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Wednesday, June 26th, 2019 AT 3:43 PM

23 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome to 2CarPros.

Hi Steve. Listen I believe I know what is happening. The code indicates the ECT has a short to battery power. What that will cause is the computer to read higher voltage from the sensor and expect it to be at least -40°F. The result is it dumps fuel to the engine and basically floods it. When you disconnect the sensor, that signal is gone and it runs in a closed loop.

Here is what I need you to do. First, turn the key off and disconnect the ECT connection. Turn the key to the run position (engine off) and check voltage at the plug. It should be around 5 volts. If it is higher, we have a short to power between the ECT and ECM. If it is lower, suspect an open circuit.

Do this and let me know what you find.

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

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

Let me know what you find or if you have other questions.

Take care,
Joe
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Wednesday, June 26th, 2019 AT 9:29 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
Okay, so I was finally able to test the wiring and it has two wires running to it. One runs directly to the computer it got 5.03 volts. The other wire runs to the throttle position sensor. The one that runs to the TPS had no voltage but it had continuity. All other wires to the TPS had around 5v to them.

Shouldn't that wire running from the TPS have voltage to it also since according to the wiring diagram it has a wire running directly to the computer? I attached the picture and circled and drew around the wire I am referring to.
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Thursday, June 27th, 2019 AT 4:37 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome back, Steven:

Is the wire you are referring to green and yellow? If it is, that is a sensor ground for several different sensors, and it does run to the TPS. That's why you have continuity. See picture 1. If it is a different color, let me know.

Now, what the heck is causing the code you have. The voltage is great, you have ground, the sensor is new, so why. I know you replaced the connector. Is there any chance when you attach the sensor that another wire is making contact and shorting to power?

Let me know.

Joe
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Thursday, June 27th, 2019 AT 6:54 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
When I disconnect the battery and let it sit to reset the check engine light I noticed the only time I get the code is when the connector isn't plugged in when I start it. Sadly the only way to get it started is to leave the connector unplugged. I checked it when the connector is plugged in there are no other wires near it. It mainly sits above the engine any other wires sit below it other than other sensors on different parts of the engine.
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Friday, June 28th, 2019 AT 1:04 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Okay, that makes sense why you are getting the code. Do you have a live data scanner that you could check what the sensor is reading? Also, I'm starting to question the ground at the ECM. One more component in that series may be enough to cause the ground to fail. Ugh. They don't make it easy.

Let me know.

Joe
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Friday, June 28th, 2019 AT 5:47 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
A live data scanner? Like an ob2 reader? Or one that does like freeze frame and all?
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Friday, June 28th, 2019 AT 6:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome back:

Yes. I would like know what the computer is seeing from the ECT sensor. It will actually say the temperature it is recognizing.

Joe
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Friday, June 28th, 2019 AT 6:50 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
The problem is no freeze frame is stored as I have cleared the code to see if it will come back. It only comes back after I disconnect the connector it doesn't give a code when I leave the connector plugged in it just doesn't start the vehicle. Will it give me a temperature from the freeze frame if the connector isn't plugged in?
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Saturday, June 29th, 2019 AT 11:01 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome back:

Honestly, that is possible, but it is based on the scanner you have. However, it should be there.

Joe
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Saturday, June 29th, 2019 AT 6:16 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
So I realized why it's not giving any freeze frame data. The check engine light doesn't come on because of that code. The obd2 scan tool shows the code when the connector is disconnected but when I plug it in the code is no longer shown on the scan tool. I have to get another scan tool the one I have now misinformed me that it reads live data when it only reads freeze frame data. Any suggestions to a budget friendly scan tool that has live data reader on it?
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Sunday, June 30th, 2019 AT 12:10 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Hi Steve:

I'm not supposed to recommend brands. However, if you watch this video on how to use a scanner, that brand is not too expensive and I have used one for years without any issues.

https://youtu.be/YV3TRZwer8k

I hope that helps.

Joe
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Sunday, June 30th, 2019 AT 7:07 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
Okay, so I have two different obd2 scanners one on the android and the other does live data. Is there any specific live data that you are looking for? As far as the sensor goes all it shows is coolant temperature. Is there a way to test if my computer is the problem?
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Tuesday, July 2nd, 2019 AT 4:47 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Steve:

What temperature is it saying is present? Does it seem correct? For example, if it's 80 degrees, does the sensor indicate that?

Let me know.

Joe
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Tuesday, July 2nd, 2019 AT 6:51 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
Yes it usually shows coolant temperatures around the temperature it is outside. Like it showed 86 the other day when it was 89 degrees out. So all seems correct there.

One thing I noticed which may just be because the car wasn't running but the fuel trim short term and long term are at 0. Also my timing advance is 63.5. How do I know if that is normal or not?
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Wednesday, July 3rd, 2019 AT 12:16 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome back:

The readings are most likely the result of not running. Honestly, when running properly, fuel trims should be as close to 0 as possible.

Okay, the sensor is working. The next thing I would check is for continuity to the sensor. If you recall, we discussed how the ground us used for a few things. However, what I need you to do is check for ground (continuity) with the key off and the sensor plugged in. Then have a helper crank the engine to see if continuity is lost.

Let me know.

Joe
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Wednesday, July 3rd, 2019 AT 5:37 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
I am just now seeing this. How do I check for continuity if the sensor is plugged in? Wouldn't I need to check for continuity from the ECU harness to the wire itself?

I know how to check for continuity to ground, I have never heard of testing it with the connector plugged in though is the problem I have. Any directions will be greatly appreciated.
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Tuesday, July 9th, 2019 AT 3:19 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome back:

In this case, you are simply testing to see if the wire maintains continuity. Also, you can check the wires itself by placing the multi meter on each side. All you are looking for is to see if there is a continuation of power flow (from your volt meter) through the wire. On the other side, simply test the ground wire at the sensor to ground to see if it fails when under a load.

Please feel free to let me know if that made any sense. It's much easier to show in person.

Joe
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Tuesday, July 9th, 2019 AT 7:32 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
Sorry for the late reply it's been raining like crazy here the past few days.

So, I checked for continuity to ground at the connector and it has continuity. I checked it with the key on engine off.

The question I have is am I supposed to test this method with the connector plugged in? Also I'm not sure I understand the testing of the wires itself by placing the multi-meter on each side.

OAN: The connector is getting 5.03v when KOEO. It has ground also. I tried plugging in another ECM to test if that may be the problem but got the same results.
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Saturday, July 13th, 2019 AT 1:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Welcome back, Steve. We have been getting the rain too, but finally have had a couple nice days in a row.

As far as using the multi meter for checking the wire from end to end, it is simple. You will be checking for continuity. Electric is nothing more than the continuous flow of electrons through a conductor. If there is a break in the wire, the flow stops or you have an open circuit. When you check for continuity in a wire, your multi meter will supply power to the wire on one end, and at the other, you are checking if the power is coming out. This is how resistance in a wire is checked. The longer the wire, the more resistance.

Let me know if that makes sense. Also, since the different ECM didn't make a difference, there has to be a break down in the wiring. Are you sure the pins you plugged into the new component were in good condition? I've seen one or two of them get pulled and then the pin isn't long enough to make contact. And as far as checking the ground, I wanted everything connected to make sure the ground can handle the full load.

Let me know,

Joe
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Saturday, July 13th, 2019 AT 9:10 PM
Tiny
STEVEN SPELLMAN
  • MEMBER
  • 13 POSTS
Okay, so I back probed the connector using a t-pin while it was connected to the sensor. It only got 3.08v when KOEO. When trying to start the vehicle to see what it puts out it only gets around 3.02v. I'm going to check it again to make sure it's not a weak battery or weak connection to the connector or sensor.

If it is only getting 3.08v when connected to the connector what could be the problem? When the connector was off of the sensor the connector itself got 5.03v. So I'm kind of lost as to what to do next. Any other advice is greatly appreciated.
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Saturday, July 27th, 2019 AT 4:04 PM

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