Engine Temperature Sensor(s)?

[Twain427]

As always, forgive me if this has been previously discussed, however a search did not immediately provide an answer.

2015 5.0. I received a message on the DIC stating the engine had overheated, and the temp gauge was pegged in the red. Pulled over, etc. and discovered the message was in error and all was fine; the engine is not overheated. Clearly, I suspected a faulty coolant temp sensor. I replaced it (located on the front of the engine) and frustratingly the issue persists. The gauge still reads as the engine is running hot (and, because of such the fan always runs amongst other irritations).

Question: Are there other temperature sensors to be addressed? TIA

 

[joegr]

How are you measuring engine/coolant temperature to verify that it is not actually overheating?

 

[carguy75]

As always, forgive me if this has been previously discussed, however a search did not immediately provide an answer.

2015 5.0. I received a message on the DIC stating the engine had overheated, and the temp gauge was pegged in the red. Pulled over, etc. and discovered the message was in error and all was fine; the engine is not overheated. Clearly, I suspected a faulty coolant temp sensor. I replaced it (located on the front of the engine) and frustratingly the issue persists. The gauge still reads as the engine is running hot (and, because of such the fan always runs amongst other irritations).

Question: Are there other temperature sensors to be addressed? TIA

The engine coolant temperature sensor is located on the lower front timing cover just to the left of the water pump. Be careful when removing or replacing the sensor since it could crack the timing cover; which will make for an expensive repair. The same goes for the oil pressure sensor; in which I found out the hard way.

The coolant sensor.

 

[Twain427]

The engine coolant temperature sensor is located on the lower front timing cover just to the left of the water pump. Be careful removing or replacing the sensor since it could crack the timing cover; which will make for an expensive repair.

The coolant sensor.

Yes, I replaced this (as I said). I am still receiving a false reading on my cluster. There must be another sensor misreporting.

 

[carguy75]

Yes, I replaced this (as I said). I am still receiving a false reading on my cluster. There must be another sensor misreporting.

Maybe you have a stuck thermostat that is not opening; hence the overheating.

The 2015 5.0 only has one coolant temp sensor which you replaced already.

 

[GenSquared]

Man this is WILD. I have a 2015 5.0 as well and just a month ago in OCT, my car gave me the same warning about the engine overheating.. Pulled over and the car was running fine, but there was coolant overspray in the engine bay. So I limped er to Advanced Auto thinking coolant leak, but adding coolant did nothing. So my car has been at the dealership outside of warranty awaiting the part to be delivered. Supposedly, the part is to be delivered this morning so I should have it back by this afternoon.

FUNNY PART, is that I dropped the car off 6 Oct, didn't hear from the manager of service until 18 OCT, which informed me of the repairs required. $576 for the coolant temp sensor $2465 for a new sunroof track assy and that they were STILL looking into the AEB and Parking Brake Light warning.

Will take about 5 - 6 days to show up. I said damn, OK. Well Friday, 28 Oct, I popped up at the dealership, looking for an update. THE GUY TOLD ME THAT THEY HAVEN'T ORDERED A SINGLE PART BECAUSE THEY WERE WAITING TO HEAR WHAT REPAIR I WANTED THEM TO PERFORM!! wtf! I told them to just take care of the fcking coolant sensor and I'll come back later for the rest because I really need my car. He Texted saying that the part should be delivered later that day, 03 NOV!!. MONDAY, 7 NOVEMBER, I was told that the wrong part showed and that the new one was on order.

Here I am, a lucky american who can have and enjoy a luxurious and safe, fast daily (GENESIS), and a daily-able 99 Pontiac Trans AM to drive on the weekend. Well that is until it breaks anyway, LIKE NOW. Something in the Rear of the brid is clicking, and I can't drive it until I fix that, and a month later after dropping my car off at the dealer for service, THE CAR IS STILL BROKEN, and I'm car-less

Lol there's no excuse for Hyundai to have my car for so long

 

[joegr]

...THE GUY TOLD ME THAT THEY HAVEN'T ORDERED A SINGLE PART BECAUSE THEY WERE WAITING TO HEAR WHAT REPAIR I WANTED THEM TO PERFORM!!...

My experience has been that outside of warranty, no parts will be ordered or repairs started without explicit confirmation from me to do so. This is true (I think) of any shop. I would not expect otherwise.

 

[Andyj]

Wow $576 for a coolant sensor sounds high. Good luck, hope it fixes the problem.

 

[joegr]

Wow $576 for a coolant sensor sounds high. Good luck, hope it fixes the problem.

I don't see how it would. Sounds like it really overheated if it over-pressurized and spit coolant out.

 

[GenSquared]

My experience has been that outside of warranty, no parts will be ordered or repairs started without explicit confirmation from me to do so. This is true (I think) of any shop. I would not expect otherwise.

I got the call from the dealer the next morning, on the 10th, that the part had showed and that the repair would be done by the end of the day. Turns out, the part was $91 and that the labor was $$536. The manager informed me that the sensor was behind the engine, between it and the firewall. Had I know I would have looked up and behind it to see if it were something I might have done myself.

I'm pretty sure the first sensor that was ordered was the one that's located on the lower front of the engine, which wasn't defective on my vehicle. But overall, I'm satified to have my vehicle back. I still me the residule cooant being burned out of the engine from time to time, but there aren't any leaks thankfullly.

Now I only have 3 more expensive repairs to have done. Have you found a good warranty that rivals the warranty that came with the vehicle? As far as the coverage goes I mean.

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[carguy75]

I got the call from the dealer the next morning, on the 10th, that the part had showed and that the repair would be done by the end of the day. Turns out, the part was $91 and that the labor was $$536. The manager informed me that the sensor was behind the engine, between it and the firewall. Had I know I would have looked up and behind it to see if it were something I might have done myself.

I'm pretty sure the first sensor that was ordered was the one that's located on the lower front of the engine, which wasn't defective on my vehicle. But overall, I'm satified to have my vehicle back. I still me the residule cooant being burned out of the engine from time to time, but there aren't any leaks thankfullly.

Now I only have 3 more expensive repairs to have done. Have you found a good warranty that rivals the warranty that came with the vehicle? As far as the coverage goes I mean.

Interesting. So the manager told you that they changed a coolant sensor located on the rear of the engine(or on the firewall)?

The Hyundai repair manual do not list a rear coolant sensor for the 5.0, only the one coolant sensor on the front timing cover. It may have been a bad coolant pipe or joint they replaced, not a coolant sensor.

 

[Twain427]

Problem has been discovered however cannot be corrected at the moment. Underneath the intake is a relatively small, plastic manifold that branches out to three separate outlets (Part No. 25420-B1600). Over the years of heating and cooling the plastic deteriorated and broke. Coolant was escaping at this point, and the system could never pressure up to adequately regulate the engine temp. Unfortunately, this part is on national backorder. Many parts warehouses will show it available, however cancel the order each time they discover they don't actually have it. My options are to order and wait, which if you've ever ordered a part that is on back order you know it could be 2 weeks or 2 years. I have a rather educated friend with a 3D printer who might be able to fabricate it, but that is also unknown at the moment.

This is a rather frustrating problem that I hope none of you have to face. That being said, if you've got a 5.0, it's just a matter of time. Made the odds be in your favor and it again become available.

 

[Twain427]

Interesting. So the manager told you that they changed a coolant sensor located on the rear of the engine(or on the firewall)?

The Hyundai repair manual do not list a rear coolant sensor for the 5.0, only the one coolant sensor on the front timing cover. It may have been a bad coolant pipe or joint they replaced, not a coolant sensor.
View attachment 49802
View attachment 49801

You were right about the coolant pipe! Unfortunate, as you'll read, I'm currently SOL.

 

[carguy75]

You were right about the coolant pipe! Unfortunate, as you'll read, I'm currently SOL.

No problem. It is messed up that you can not get the part you need anytime soon. A plastic coolant pipe should be easy to replace.

You could try using some epoxy and thermostat RTV sealant to perform a temporary repair to the current pipe until a new pipe becomes available.

 

[alnn]

Problem has been discovered however cannot be corrected at the moment. Underneath the intake is a relatively small, plastic manifold that branches out to three separate outlets (Part No. 25420-B1600). Over the years of heating and cooling the plastic deteriorated and broke. Coolant was escaping at this point, and the system could never pressure up to adequately regulate the engine temp. Unfortunately, this part is on national backorder. Many parts warehouses will show it available, however cancel the order each time they discover they don't actually have it. My options are to order and wait, which if you've ever ordered a part that is on back order you know it could be 2 weeks or 2 years. I have a rather educated friend with a 3D printer who might be able to fabricate it, but that is also unknown at the moment.

This is a rather frustrating problem that I hope none of you have to face. That being said, if you've got a 5.0, it's just a matter of time. Made the odds be in your favor and it again become available.

View attachment 50131

I believe I may have found this part available separately as a connector, part code 28485B model code 3F400 matching our 2015 5.0's. It's also much less expensive to acquire (~$10-$15) and is likely being supplied by a different manufacturer in SKR since the original manufacturer of the hose assembly stopped making them (likely due to Tau being discontinued?) and HMA is seeing more reports of 15-16 5.0 owners with broken connectors.

Am I looking at the right part here? This diagram seems to confirm it:

 

[Andyj]

Do you mean part 25484B in the diagram?

 

[alnn]

Do you mean part 25484B in the diagram?

Yeah that was my typo, 25485B but there's two model identifiers, B1600 and 3F400, not sure which is specifically that connector in the hose assembly.

 

[alnn]

I wanted to update everyone that part number 25485B-B1600 and 25485B-3F400 is the correct connector that is part of the hose assembly for fixing these coolant leaks. I will say that the latter part (3F400) is for my specific 5.0 because I noticed the side that hooks up to the O-ring and the inlet hose to the thermostat is recessed, whereas the B1600 is not, so you may not have as much of a tight fit to the inlet hose if you go with the wrong model identifier, I'd check to see what month and year your 5.0 was built because there was a slight change made after the car first went into production.

I spent all of this Sunday morning and early afternoon performing this repair with the help of a couple of buddies with auto mechanic experience. It was quite a feat starting with the disassembly of the air intake down to the intake manifold and the protective harness housing that sits on top of the rear engine (lots of bolts (10mm and 12mm back and forth, why couldn't Hyundai just settle with one bolt size?!) and hose clamps to deal with along the way) but after about 3 hours we were able to get this part replaced along with a new thermostat, flush the radiator and pour the new coolant in and burping the system to ensure there's no air trapped, and it's now running beautifully.

I hope other 5.0 owners will find this information valuable as it's only a matter of time before this plastic piece just won't take all the constant cooling and heating any longer. Just be glad you don't need to spend all the money on a hose assembly part that's on indefinite national backorder and at least 10x the cost when the connector itself is readily available for your dealership/online parts store to order and deliver to you within the week for less than $20.

 

[QPete83]

EUREKA! I have a 15 3.8 Ultimate and have been having this exact same issue!

I took my car into Hyundai in March didn't get it back until June and two days after I got it back I started to get the error again. They asked me to bring it back and after keeping the car ANOTHER month with no updates they hit me with a failed head gasket and an engine replacement at 12k$ I was like you guys are full of it! and went and got my car back.

Have been looking for solutions ever since. This may just be the smoking gun! I'm thinking of going to a different Hyundai to get this checked out or should I go to an independent?

 

[Andyj]

Is the same connector part common to the V8 and V6 motors?