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Temperature Gauge Problem

61K views 93 replies 21 participants last post by  jhoravi 
#1 ·
I don't know what to do anymore. 3 Mechanics, hundreds of dollars, and no answers. I just want this fixed.

Anyways,

I have a 2006 Hyundai Sonata GLS 3.3L V6 that has been acting up recently. The actual problem I am experiencing is an "overheating engine," but I have had many tests done that say otherwise.

The car will remain at normal operating temperature while driven at all times, except for when I turn on the air conditioning unit. Then the temperature gauge slowly climbs into almost the red zone until I turn the air conditioning off to remedy the problem.

The first mechanic I took it to thought it may have been a clogged radiator, and we did a full radiator and coolant flush. This did absolutely nothing for the problem. I then had them check all components of the coolant system, namely the water pump, thermostat, electric fan, radiator; and everything seems to be operating correctly.

The second mechanic thought that maybe since the water pump and the air conditioning compressor share the same accessory belt, that engaging the air conditioning may have been causing the water pump to become underpowered and not act normally. Upon checking tensions, everything seemed fine and the pump was definitely "pumping."

The third mechanic thinks that there may be a problem with the temperature sensor itself. He ran the engine up to "extreme conditions" aka 5000rpm stationary to see if it would overheat, and using a thermometer showed that the coolant was indeed doing its job even with no airflow. He checked and re-surfaced the grounds for the electric fan and the power relays and everything seems to give the proper voltage. The only thing we have not yet done is replace the coolant thermometer.

NOW.

I'm SOO DONE with all the get up and go around it's giving me a migraine just writing this post. If anyone has experienced similar problems, please let me know, and possibly my mechanic so he may know how to fix this.

Thank you.
 
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#2 ·
Monitor engine coolant temp in current stream ??

Only over heat we see is usually when customer complain the A/C works for bit, then stops.. excess engine temp shuts off A/C command in the pCM.. look for lower radiator hose to have green/white crust growing at end of lower hose where it mate to fitting..

We have seen random fan control module fault at left frame rail.. scan PCM for DTC
 
#3 ·
Did any of your 3 mechanics think to check engine temperature using the diagnostic scan too?

On Hyundai there are normally two temperature sensors inside the one component. One is for the gauge on the instrument cluster and the other is the temperature signal for the engine computer. Electrically they're both completely independent circuits. On most cars the engine temp gauge should hover around half way when the engine is up to normal operating temperature. If your gauge is way past half way and the coolant temp data pid on the scan tool says 90ish 'C (195 'F) then the gauge is incorrect and your looking at an electrical issue with the gauge circuit rather than a coolant flow/cooling fan problem.

Scottie.
 
#5 ·
Thank you all for your input. I'm about ready to lose my mind. He just replaced the temperature sensor in hopes that it was just malfunctioning, which again did nothing. I don't really know what to do at this point. I'm just a college student and I don't have the time or money to keep putting into this.
 
#7 ·
He just replaced the temperature sensor in hopes that it was just malfunctioning
Did any of your mechanics think to try disconnecting the sensor to see how the gauge responds? If it still shows hot with the sender disconnected then it's not the sender, or a coolant flow/cooling fan issue. Look at that. I've maybe just eliminated all the things the 3 mechanics have spent hours checking in about 30 seconds :).

nforshee93 said:
I don't really know what to do at this point. I'm just a college student and I don't have the time or money to keep putting into this.
I think the most important thing to do in that case is make sure that the engine isn't actually over heating (it doesn't appear to be). If the fault is just a gauge error then there is no mad rush to fix it. If the engine is overheating on the other hand then obviously you need to deal with that ASAP.

Scott.
 
#8 ·
Overheating???

Greetings, Wow! I'm amazed at the conclusions these 3 "apparent mechanics" (here-by, AM) came up with! I only hope none of them were actual Hyundai Line Mechanics. As mentioned earlier there are several other possible causes to even get to the conclusions reached by the AM.

1st, is it actually overheating? Such a difficult concept to grasp... then, while waiting for it to warm up, check all the involved fuses. Replace if needed. Is the fan working? I'm not sure of Hyundais but in general, radiator fans activate when the A/C is turned on. If not but the fan works as it is supposed to in regular service, a sensor or switch could be responsible.

This is a brief "follow the workflow" but as mentioned by SBR711, scan the codes via a dealership. Also as Red Raspberry suggested the Android app, Torque could be a valuable tool for your kit.

My final suggestion would be your dealership. With the funds you've exhausted on 3 AM's your situation may have been resolved for about the same price. Maybe?

In conclusion, no more good money after bad and hopefully a qualified technician that is reliable and trustworthy... that's a mouthful! :surprise: Good luck with your NF. I hope the answers you received here from members helped resolve your situation.
 
#11 ·
Hello guys and gals

Wanted your input as I was having some over heating issues. Tried to find the original thread I bumped but can't find it/

My gauge sky rocketed during these Texas hot summer days. We finally did confirm it was running hot. The mechanic that worked on it initially swapped out the temp sensor and it was stable at idle even when it was extremely hot out. As soon as I drove it, it went back up. So definitely, the car was over heating based on the readings on his scanner.

We just changed water pump and radiator (I have over 200k so I figured it's probably a good idea).

He did a test drive for 30 minutes and drove it hard and gauge didnt budge. I drove it and it seems the needle went up a bit when I drive it hard on the highway and while really hot out (it's about 98-103 consistently here these days).

I put my OBD and studied my torque app - Essentially it will go up to 202 and that's when the needle jumps a bit. About half walk in between the center and next marker.

We are thinking maybe some air pockets in the cooling?

I know these cars should not run hot at all - The 3.3 in my 09 Azera stays quite a bit below the half way mark no matter how hard I drive it. Same for my 06 3.8 azera. The radiator was bought from Amazon and water pump is oem.

Any ideas before I bring it back to mechanic?

Thanks
 
#12 · (Edited)
It really takes a two or three heat/cool cycles to purge all the air out. And if there is even a minor leak then that does not happen. To check, look at the radiator before you start the car for the day and top off. It should always be completely full when cold.

And don't trust your OE temp gauge to warn you of problems
 
#13 ·
Just open the cap and see if it's all the way to the top correct?

My neighbor also noticed that when the mechanic re-clamped the hoses with that circular clamp, he didn't put it on the same exact spot - There is an indentation you can see on where it was initially positioned. Seems kind of minor but I guess I will move the clamp to where it was initially positioned.

Looks like there aren't any leaks, I looked around both hose ends.
 
#15 ·
A couple more knoob questions:

I watched some videos on youtube on how to get the air out (i.e. bleeing the cooling system).

Where abouts is the bleeder valve for the cooling?

Also, do I need to put the HVAC temp all the way to hot and put the fan on low setting? Not sure if that one pertained to our cars or what not.

Using this video as reference btw.
 
#16 ·
There is no bleeder valve and tuning on the heater does nothing but take the car longer to warm up. There is always coolant flowing through the heater core. You may have a small coolant hose that is near the top of the engine to bleed air out when filling.

There are many tiny pockets where air will get trapped and no way is squeezing hoses, putting the nose in the air or special funnels get all the air out. Some has to become dissolved in the coolant as the pressure rises and then when the excess pressure pushes the coolant out the air also goes out.

That is why it is imperative for there to be no leaks at all.
 
#17 · (Edited)
Pre-fill via upper hose, this will fill block and heads, with the thermostat being the gate at lower hose,, when upper hose close to full, put it back on radiatior neck, and finish fill radiator now..

Use fill funnel 1/2 full of coolant and let engine run till fan run a couple time, then cap the radiator..

Add coolant to reserve bottle a little over the "F" mark.. drive away and let cooling system finish itself (may note slight level change in bottle)

 

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#18 ·
Unless there is an issue with the temp sensor for the gauge then it sounds exactly like when I had ground issues on my car.
Cleaned up all round connections and the problem went away for a little while.
Added extra ground leads and not it has not returned.
 
#19 ·
I did read the other threads relating to this issue. So, I initially thought my issue was also this ground problem; specifically when I added HID to this new set of headlights I got. But the car is actually over heating when on the scanner....was yours actually overheating? The mechanic checked all the other grounding points but i am not sure it's the issue with mine.....

I am not sure though.

Where did you add ground leads? wondering if a grounding kit would help. But my car is definitely not cooling properly.

Heater is not working that I can tell, so I am thinking I still have air pockets in the system.
 
#25 ·
So, I test drove and put the scanner on my 09 Azera...it actually has the same motor as the NF (3.3).

It's 103 something and heat index is 115 outside so it was a good day to test it out.

It doesn't go over low 190s no matter what I throw at it. Is that what I should be getting in my NF if the cooling system is working properly??

The gauge needle in the Azera seems to be a little off. I know it's not meant to be super precise, but the needle seems to point a little too low for what it's reading.
 

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#26 ·
Hyundai's temperature gauges are not meant to judge the condition of the cooling system. They generally are good for it's cold, OK and too late.

The fan isn't even set to turn on until over 210f at idle.

To really know use the OBDII device. I have an UltraGauge that I just leave connected all the time on my Accent.
 
#27 ·
My 2005 Optima with the 2.4L will read anywhere from 188* to 208* depending on how hot it is outside and if I'm climbing a hill at moderate speed.
During these temp changes the temperature gauge will remain in one place, won't move at all - just a little below half.
So the accuracy of the gauge leaves a lot to be desired.
The car has never acted like it was overly hot but the gauge did go crazy before adding the extra ground leads.

I added one from the negative terminal of the battery to engine, one from the firewall to the intake assembly, one from the right shock tower to the alternator and one from the negative terminal to a plate on the engine right where the ignition module is mounted.
 
#28 ·
Well, still running hot.

I did try to burp the system and I noticed some bubbles (quite a few of them) in the funnel. It actually seem to run cool-er ultimately it was still above the average I am getting in my Azeras under the same conditions.

Took it to a local Hyundai dealer to have them do a coolant flush and was hoping that would solve the issue.

It is still running hot. Not really sure what should be consider "normal" for the 3.3 V6, but 210 I think is way too hot. Right? The gauge went crazy as well.

So far, I have put in a new radiator, new water pump, new thermostat, and new temp sensor. What else could it be?

I know the next much worst issue could be the head gasket, but could the cooling system still have air in it?
 

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#31 ·
The AC will turn on the radiator fan. Usually lo speed fan below 35 mph or so and then his speed if the AC pressure gets too high.

I just put in new t-stats this summer in my Genesis Coupe and Accent. Both had been reading at 180F-185F/ Usually 180F. Both cars have the same t-stat too. But on both cars now they run 187F.

The Accent is real sensitive to the wind as far as cooling goes too, running 5F or so hotter with a tailwind.
 
#32 ·
So, I took out battery tray and air intake box by the hood latch to get easier access to that radiator fan controller. Wanted to take it off, but was nervous about breaking the clips. It has 2 main wiring harness hooked up to it. I did follow the ground points on it and essentially ran them to the main ground on the battery. I also shaved everything to bare metal so that they may get better contact.

I'll do some test drives here in a bit when it gets crazy hot out again.

I am thinking my issue could be a grounding hickup somewhere. This overheating initially came about when I re-installed my HIDs on these new headlight assemblies.

Judging by what I have been reading here, the grounding issue could be my case.

When the car is idling (AC full blast) and it's hot as **** out, the car's coolant temperature reads stable. As soon as I drive it above 4k rpm, it starts to creep up. So maybe the fan (low) is not kicking on when I am driving. I think it does kick on when it hits the hot mark (210 or so) or the AC is making it kick on, but when driving normally, maybe the fan is not on like it should be?

I saw a youtube video of a guys testing the harness on a radiator fan...looked like it had two harness, one for high and one for low. I am guessing ours doesn't have that and the controller is what tells the fan what to do. How do I test the controller and know it's good?

Looks like a 180 dollar piece at rockauto.
 
#33 ·
When driving down the road there should be little need for the fan. Only under extreme AC load would this happen and then it would be the AC pressure triggering this, not coolant temp. With my AC on I seldom see temps above 190F on either car.

but temps here seldom get above 95F.

You should see if the car runs cooler or hotter with the AC on or not and driving down the road.
 
#34 ·
Yeah, both my Azeras do not go above 195 on the scanner - it'll hit 198 for a sec and itll go back down. This is under extreme conditions.

It gets pretty ridiculously hot here though. But the readings should be same as my other two cars. They are very similar if not essentially the same cars.
 
#38 ·
When I am idling and press the AC button, I do notice the fan kicking in.
I am not sure about what it is doing when I am driving though.

Drove it again today and drove my 09 Azera and really looked at the coolant numbers.

It will go up to about 212 and really will hover around 200-210 while driving for a prolonged period. I really don't want to blow up the car so I do not want to push it just to find out how high it will go. The only time it will lower is if I am idling with AC on and it will slowly drop down.

Something is definitely not right. I drove my Azera right after with same conditions and drove it way harder and coolant temp will not budge over 195 or 200 max. More importantly, I notice it drop down right after and will stabilize at 195ish no matter what I throw at it.

I have had this Sonata for more than a decade living in the same city so this is definitely not normal and the outside conditions/factors are the same. Not once has the temp gauge budge in those 11 years.

Also took apart my dash and swaped out the module for the temp needle (just thinking it was a quirky thing when I did my led swap on the dash). Same results though. The needle is sensitive after 205 ish but I think it's working properly.

It looks like the dash just tells you it's hot rather than actual temp. Having said that, I notice it will slowly go up once I hit 206 and basically when it hits 210 and above it will go up pretty quickly at 3/4 mark.

Maybe something to do with a fan. That's what I am looking at next.
How would I be able to tell if fan engage while I am driving? Should it? I assume yes if the temps go up it should to try to keep the radiator cool?
 
#43 ·
Couple more knewb questions as I am burping the system in the mornings.

- Should I put the AC on while the car warms up to operating temperature when I am trying to burp the cooling system? Or does it matter?

- Where exactly is the coolant temp sensor? I may try to test its resistance and make sure it's working.

- Coolant temp sensor unit is both the sensor and sender on these cars right?

- I noticed on my OBD reader, without the AC on, the dash needle will not move above mid marker even at 210; when I press the AC on, I think the fan kicks so the temp reading on OBD drops down, but the needle on the dash goes absolutely crazy and skyrockets to H....even when ECU reading is going down to 195. What could be the reason for this?


Any inputs appreciated.
Thanks

:D
 
#44 ·
This was the same exact issue I had with my '05.
Turned out it was bad grounding in the electrical system, especially the gauge panel.
Added my extra ground leads and the issue has never returned.
Before I added the extra ground leads I actually turned around and slowly went home one day when the temp gauge shot up to a little over 3/4.
But unlike with other cars, my turning the heater on full blast and turning off the AC didn't help at all. In fact, the extra load on the electrical system made the temp gauge creep up a little higher.
Got home and plugged in my OBDII reader and found that the ECU engine temp was fine, just the gauge going crazy.
Did a little internet searching and came across a number of posts about bad grounding for the cars.
Cleaned up the existing ground leads and the issue went away for a little while.
Added the extra ground leads and everything has been fine ever since.
 
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